Doug Wimbish used to, until he was bought up by Ibanez. His signature Ibanez is a copy of a Spector in everything but body shape. I'm sure he still uses Spectors in the studio. Jason Newsted also used one for Metallica's '90s albums, along with an Alembic Europa, a Zon Legacy fretless, and possibly those Sadowskys he schilled (sp?). Flea has been known to use a Spector in the studio, as has John Myung. Of course, the most famous Spector user is Mr. Gordon Sumner, who made one famous with the Police in '83 and '84. He has his own signature Fender now, but that white NS-2 is certainly a classic.
Check out this link to the Spector website...this will give you a better list... http://www.ssdbass.com/NewFiles/gall.html
Spectors were pretty wide spread in the 80's and early 90's. It seemed like every artist owned one. They're not as prolific as they were, probably because there are so many nice mass produced basses available now. However, I still think they are one of the finest basses ever made.