Jack off Jill split up in 2000. EDITED TO ADD: Jack off Jill have reformed and have played some live dates in 2015.
(For information on Jessicka and Helen Storer please use the relevant tags).
Robin Moulder (Agent Moulder) founded TCR along with TC formerly of the band, Triggerpimp and they released an album called The Chrome Recordings in 2004 (which also featured contributions from former JOJ members Chris Vrenna and Scott Putesky). Robin is now married with two children.
Tenni Arslanyan (Tenni Ah-Cha-Cha) who co-founded the band along with Jessicka and Michelle Oliver (Michelle InHell) founded Set to Zero. In 2010 Tenni began playing with Zombie Queen.
I know the soundtrack to Down and Out With the Dolls features a song by a band called Lo-Ball that had Claudia Rossi in but I've never been able to find out anything more about them. Claudia founded a band called One of the Loudest Tragedies Ever Heard and apparently skates for the Angel City Derby Girls.
Laura Simpson (Lauracet Simpson) and Jeff Tucci (Ho Ho Spade) are apparently now no longer in bands and are both working in the Florida area.
Scott Putesky (SMP, also known as Daisy Berkowitz when he was with Marilyn Manson) filed a lawsuit against Marilyn Manson after he left/got kicked out of the band (accounts vary). He used to play in a side project of Jessicka's called The Linda Blairs as well as being in Jack Off Jill for about a year.
He formed a band called Three Ton Gate. He then had a band called Rednecks on Drugs which evolved into Stuck on Evil who recorded an album called Suntanic in 2001 beforre reverting back to the name Three Ton Gate. He joined Kill Miss Pretty in July 2010 and is working on a new album with them.
Chris Vrenna and Clint Walsh play in Tweaker. They've released two albums, The Attraction to All Things Uncertain and 2 A.M. Wakeup Call as well as EPs and singles. They've both played as part of the live band for Gnarls Barkley (and Clint has also played guitar for Juliette Lewis and the Licks among others).
Tweaker's official website
Chris Vrenna was also the drummer in Nine Inch Nails as well as working as a producer for artists like David Bowie, Metallica, Smashing Pumpkins, Hole, Marilyn Manson and Rasputina. He's also done the music for several videogames such as Doom 3, Enter the Matrix and American McGee's Alice. He's now the new drummer for Marilyn Manson
Norm Block now plays drums for Mark Lanegan.
Official Jack Off Jill website