Forever 7.
Well, I'm not actually sure how many people we have off the top of my head. Let's see...
Me, Infinity, PX, Amra, Shadowbringer, Helepolis, Pesco, Dular, Panda, Loolicon, DollS, Trance, ActionDan, YoukaiJesus, Yukarin, Thanuris, RV29, Apharmdb, Magna, headcrabs, WhiteWish, FFMaster, Kaito, and some others that I'm probably forgetting.
Of course, some play more frequently than others, so I guess ~20 would be a good estimate.