Dean worked with the band 10 Years on their album 'Division'. He co-wrote the song 'Focus', but does not play on it. 'Division' is 10 Years's fourth studio album and second major label release, released May 13, 2008.

'Light It Up', the title track off of Rev Theory's album, features Dean DeLeo on additional guitar. The album was released on June 10, 2008 through Interscope.

Dean and Robert DeLeo wrote songs with Peter Frampton before they went on tour with STP. They plan to record with Frampton after they get off the road in November.

Dean contributed to the soundtrack for 'In The Land Of Women,' which was released by Lakeshore Records on April 17, 2007. He is credited for playing guitar on the album, but the credits do not specify on which track(s). It is most likely that he played on the Stephen Trask tracks 'Out Of His Mind' and/or 'In The Land Of Women'.

On November 14, 2006, Army Of Anyone release their self-titled album.

Dean DeLeo appeared on the Chicago album 'XXX', released on March 21, 2006. He played guitar on the song 'Better'.

In September of 2005, Dean and Robert DeLeo got together with Filter singer Richard Patrick for a songwriting session. The session went so well that they soon decide to form a band. Eventually they team up with David Lee Roth drummer Ray Luzier to form 'Army Of Anyone'.

Dean and Robert DeLeo worked with Seal in 2005. Robert DeLeo wrote on the Army Of Anyone official site forum in 2007: "I have to say Dean and I got together to write with Seal [in 2005] and we did a loose, rough recording of 'About A Fool' and it floors me every time I listen to it. He is an amazing talent. Seal right in front of me singing while we were playing made me cry. I could only compare it to what it would have been like in front of someone like Marvin Gaye. I mean that.".

Dean appeared in the documentary 'All We Are Saying' by Rosanna Arquette. 'All We Are Saying' is "a compelling, personal look at what makes musicians tick. Rosanna Arquette follows up her critically acclaimed documentary directorial debut, Searching for Debra Winger, with a look into the psyches of some of the top musical artists of the day." (Source: IMDB.com)

In January of 2005, Dean and Robert DeLeo played in a short-term project called 'Farm Fur'. Robert posts about this on the official STP site's forum: "Hi Everyone, It's Robert. I can confirm that Dean and I will be playing with Farm Fur, but for only 3 shows. Our friend Steve Ferrone asked us to sit in, and we were honored to be asked to play with such great musicians. It's a lot of fun. It's a 10 to 12 piece band, a bit different from what Dean and I have ever done. The songs being performed are musical contributions from each artist or band the artist is from."

He continues: " The set will include songs by The Average White Band, Sly and the Family Stone, Rufus, Steve's solo stuff, as well as a couple STP songs. The STP material isn't intended to be played like STP. It's a one-time chance for Dean and I to take a couple of our songs and perform them with some of the best musicians on this planet. Would you pass that up? Farm Fur is certainly not a long-term band. It's a chance to have a hell of a lot of fun, and be be musically challenged by some pretty intimidating players."

He also explains the band's name: "Dean keeps his horses at a ranch that has a lot of unique animals. One day a zebra jumped the fence and made it with a donkey. (No shit) The result was a donkey-like animal with a black and white mane, and black and white legs only- but the rest donkey. We took a picture of this animal, which we affectionately refer to as a Dizonkey, to rehearsal one day and everyone cracked up. Dean actually came up with the name Farm Fur. We put the two together, and thought it was funny as hell. We're playing the 14th at BB King's, the 15th at the Malibu inn, and the 21st at the NAMM show. (I repeat, this is not intended to be a serious long-term band.)"

In 2004, Dean released a solo instrumental called 'Once Upon A Tribe' on the compilation cd 'Sing A Song With Six Strings,' which also featured songs by Marc Ford, Chet Atkins and Peter Frampton.

Dean is also featured in the movie 'Big City Dick: Richard Peterson's First Movie', which is described on IMDB as: "a captivating journey into the world of a savant street musician and his lifelong struggle to become a successful recording artist, and to be loved. He is a street trumpeter and part-time guest on a local rock radio station. Richard Peterson fills his world with obsessions, like "Sea Hunt" (and the "Son of Sea Hunt," Jeff Bridges), the "The Golden Age of Television" production music (which inspires four albums/CDs produced with help from the Seattle music scene), stalking local TV celebrities, and a fanatical interest in Johnny Mathis. The unique relationship between Richard and Mathis is the catalyst for one of Richard's most remarkable compositions, "Love on the Golf Course". Between street gigs and a stint as a piano player in a grunge club, mega-band " The Stone Temple Pilots" discovers Richard's music. Richard's moment in the spotlight is short-lived when he is confronted by the human cost of obsessions, revealing the dark family secret he has lived with his entire life"

In 2003, Dean and Robert DeLeo worked together as producers on the Alient Ant Farm album 'TruAnt', which was released on August 19 of that year. Dean is not credited for any instruments on the album.

In December, rumours started floating around on the internet that Dean and Robert DeLeo were starting a band with Black Crowes members Chris Robinson and Steve Gorman.

Dean played guitar on two songs ('21 Things I Want in a Lover', 'Precious Illusions') on Alanis Morissette's album 'Under Rug Swept,' which was released through Maverick Records on February 26, 2002. Later that year, Morissette released a CD/DVD package called 'Feast On Scraps', which features Dean on two additional songs: 'Fear of Bliss' and 'Unprodigal Daughter'.

Dean co-wrote the song 'Better Than The Sun' on Chris Robinson's album 'New Earth Mud', although he doesn't play on the cd version.

Robert DeLeo has spoken in interviews about his love for the country-pop performed by Johnny Cash, Jimmy Webb and especially [Glen] Campbell. And last year, Campbell's budding musician son Cal introduced his dad to the music of the Pilots. Soon after one of Campbell's Los Angeles shows, the band went backstage and met the legendary singer/songwriter. They all got along so well, Campbell invited DeLeo, his guitarist brother Dean and drummer Eric Kretz to record versions of classic cuts such as "Wichita Lineman" and "By the Time I Get to Phoenix" with him. [...] About three months ago, Robert and Dean entered the studio with Campbell to work on the new material. So far, they've written a handful of tracks, but Campbell's manager emphasized that they're all works in progress at this point and was unwilling to describe them. (Source: MTV News, May 22, 2002)

Dean commented on 'Days Of The Week', off of STP's 2001 album 'Shangri-LA DEE DA': "After I wrote that song, I received a phone call from Sheryl Crow saying she wanted to get together, so I kind of wrote this one for her. But when Scott heard it, he wanted to keep it for ourselves." There is no information available about any writing sessions Dean had with Sheryl Crow.

Dean also worked with Stephen Trask, who was producing a band called Nancy Boy (featuring Donovan Leitch, vocals, Jason Nesmith, guitar, Terry Fox, bass, Mike Williams, drums). Dean played guitar on their album. Unfortunately there is no additional information about this project. It seems like these recordings were never released.

Dean appeared on a remix of the Wallflowers song 'Letters From The Wasteland'. Scott Weiland also provided additional vocals for the 'Tom Lord-Alge" remix. The song appears only on a promotional cd for the single and on the Wallflowers single 'If You Never Got Sick'.

In October/November, Dean sits in the producer chair for the Seattle band Laughter Train, featuring Jake Priode (vocals, guitar) Jeff Yates (bass) Nathan Levans (lead guitar) Andrew Erich (drums). They recorded material at Tree Sound Studios in Norcross, GA. Dean tells Yahoo News on November 8: ""I just got done producing a record on [the] 550 [record label]. The band is called Laughter Train, and I got to co-write and play some guitar on that."

DeLeo explains how he got involved in the project: "A friend sent me some demos of them, and the singer is phenomenal--a very talented guy by the name of Jake Priode. [But] his band was terrible. His band was really awful. It sounded like a bunch of guys falling down stairs, but I knew Jake had it. He was very, very talented. I thought if I was able to get a hold of this and kind of souse things out, I could make a good record with Jake." DeLeo says the production experience gave him a new appreciation for the versatility of Stone Temple Pilots producer Brendan O'Brien, noting, 'You have to wear a lot of hats.'".

On September 21, 1999, Dean played with Robert DeLeo and Eric Kretz as the backing band for Michael Cerveris, who plays Hedwig in 'Hedwig And The Angry Inch'. They performed nine songs at Club Vynyl in Hollywood, including a version of STP's 'Big Bang Baby', which Cerveris dedicated to Scott Weiland, who is serving jail time at that moment. The show, which also featured 'Hedwig' co-creators John Cameron Mitchell and Stephen Trask, celebrated the start of the West Coast production of 'Hedwig,' which was produced by David Bowie.

Dean appeared on the Local H track 'Cool Magnet', playing the guitar solo at the end of the song. It's on the album 'Pack Up The Cats', which was released by Polygram Records on September 1, 1998.

Talk Show, featuring Dean DeLeo, Robert DeLeo, Eric Kretz and singer Dave Coutts, released their self-titled album on the Atlantic Records label on September 3, 1997. The first and only single from the album was the track 'Hello Hello. They toured in support of the Foo Fighters and Aerosmith.