We've all had our thing. I listened to the Monkees when I was little kid.

(banjo on the Lynyrd Skynyrd cover "Tuesday's Gone")
1998 – Bloem de Ligny – Zink (vocals on the track "Capsule")
1999 – Tom Waits – Mule Variations (on the track "Big in Japan")
1999 – Kenny Wayne Shepherd Band – Live On (on the track "Oh Well")
1999 – Limp Bizkit – Significant Other (vocals on the hidden track "The Mind of Les" bass and vocals on the outtake "Hell of a Band")
1999 – Phonopsycograph Disk – Live @ Slim's / Turbulence Chest (additional bass on 8 of the 12 tracks)
2002 – Gov't Mule – The Deep End Volume 2 (bass and vocals on the tracks "Greasy Granny's Gopher Gravy" and "Drivin' Rain")
2003 – Gov't Mule – The Deepest End Live In Concert (bass and vocals on the tracks "Greasy Granny's Gopher Gravy" and "Drivin' Rain")
2004 – Tom Waits – Real Gone (on the tracks "Hoist That Rag" "Shake It" and "Baby Gonna Leave Me")
2004 – Jack Irons – Attention Dimension (on the Pink Floyd cover "Shine On You Crazy Diamond")
2005 – Adrian Belew – Side One (on the tracks "Ampersand" "Writing on the Wall" and "Matchless Man")
2005 – Gabby La La – Be Careful What You Wish For. Les composed several songs for the Wii game Mushroom Men released in December 2008. A close family friend Rhys Hickman taught him the basics of the slap bass technique which he mastered throughout his educational period.

Claypool has also self-produced and engineered his solo releases from his own studio "Rancho Relaxo". Claypool's playing style on the electric bass mixes tapping flamenco-like strumming whammy bar bends and slapping.