Coalition to Stop Gun Violence
Check out their "Just the Facts, Please" segment.

Handgun Control, Inc. and the Center to Prevent Handgun Violence
These are the gun control organizations chaired by Sarah Brady, wife of former White House Press Secretary James Brady, who was shot and disabled in the 1981 Reagan assassination attempt.

Tim Lambert's archive on gun control
Professor Lambert is a top-notch statistician who crushes pro-gun arguments on the web with ease. Here's an archive of his best postings.