Snooker requires plenty of skill. To be a decent player you've gotta think at least three shots in advance, and get your positioning almost spot on every shot. It takes ages of practicing to string together a break of more than 30 (something I've never managed lol), and what must be an eternity to get a maximum 147.
I also find darts requires alot of skill too. There's not really any middle ground, you're either good (can hit trebble twenty fairly consistently) or crap (miss by a cm and hit 1 or 5 more often than trebble twenty). I know it's played by unfit fat blokes more often than not, but the levels of skill is impressive, even if it's quite specific.
Out of all the sports I've personally played (rugby, football, basketball, swimming, mountain biking, golf, cricket, aethletics, baseball, pool, snooker, darts) that those two require the highest levels of specific skill.
If were talking about a broad skillset then it's tough to beat something like the decathlon, although technically that's more than one sport grouped into one I suppose. Football and basketball along with playing a technical rugby position like outside half. MMA as Olyy's mentioned is another that requires quite a broad skillset.
Probably forgotten some.