Very powerful and fairly sickening graphic at HuffPo right now. (Link here. It actually plays, counting up the days and number of dead.) Screen shot:
The accompanying article.
Credit page says "By Jay Boice, Aaron Bycoffe and Andrei Scheinkman. Research by Jason Cherkis, Peter Finocchiaro, Adam Goldberg, Mark Hanrahan, Benjamin Hart, Alana Horowitz, Melissa Jeltsen, Chelsea Kiene, Brad Shannon and William Wrigley." Great work, gang.
@GunDeaths on Twitter.