Alison Mosshart has been involved with several musical collaborations.
In 1999, Mosshart sang vocal parts on "The State Of 6AM" and "Voice Of the Actors" with the Gainesville hardcore punk band Palatka on their album "The End Of Irony" (released by No Idea Records).
In 2002, Mosshart sang the song "No Smoke" on The Foundation Band's EP Homecoming.
In 2005, Mosshart sang the song "Old Child" with the French rock band Dionysos.
In 2006, Mosshart also sang a duet along with Brian Molko on the title track for Placebo's 2006 album Meds.
She also sings backup vocals in the song "Dolls" with Primal Scream from the album Riot City Blues released on 2006.
Source: Wikipedia