I only chose games I've not yet played, or at least not in their current incarnations.
My list:
CoC6e - I've not yet had a chance to run BRP-based CoC (just the hated d20 version), I only own the 5e book, and I've never had a chance to
play CoC at all. One of the guys in my group is a BRP/CoC/RuneQuest fan from
way back, though, so hopefully I'll get a chance sometime soon.
C&C - Just to see what all the hype's about. (I'm a big fan of "rules-y" d20, but that doesn't mean I couldn't get down with a rules-lite system, for a change.)
D&D3.5 - Similarly, while I've house-ruled in plenty of stuff from the 3.5 SRD in my 3.0 game (skill uses and DCs, mainly) I've never actually played a game with the 3.5 core rules.
d20 Modern (all three flavors) - One of the guys I work with is a big fan of d20 Modern, and we brainstorm on ideas for our respective campaigns. From what little I know of it, it sounds like a good time.
HackMaster -
I waste him with my crossbow! Seriously, I have the feeling that I will quickly become addicted to this game if I touch it. I'm fascinated by the 1e feel and the Garweeze Wurld setting. Possibly one of my next RPG purchases.
Paranoia XP - I've always been curious, I'm definitely a conspiracy guy - After all, you're not paranoid if they really
are out to get you.
Shadowrun 4e - The internet Shadowrun community seems to be sharply divided on the new ruleset (gee, wonder what
that's like?

), and from what I know of it the 3e task resolution system seems more to my taste, but my resident Shadowrun GM has looked it over, and he's converting his on-again, off-again campaign over to 4e - so I guess I'll find out the hard way. (Like there's another way in Shadowrun.)
Warhammer FRP - Didn't actually check this one, and I'm not quite sure why - I'm a GW fan (the sc-fi stuff, mainly, but still), and the dark style (at least from the early '90s stuff that I've read) would be right up my alley. I remember this one being big at the Gamer's Guild back when I first got into the hobby, but I never tried it.