Yeah Im going to agree with the guy on the first page, Johnny Greenwood is amazing... not necessarily insanely fast or anything, just unique and good!
2 of my other favorites are:
1. Matt Bellamy (MUSE)- I think him and Johnny Greenwood are in the same class, not the most amazing ever but they have some really unique sounds, and they know how to use effects to make their playing
better, unlinke many guitarists out there...
2. Mark Tremonti (Alter Bridge)- He is a really good songwriter, and I really like alot of his riffs and solos.
And since some people are talking about bassists, might as well throw in 2 of my picks on them...
1. Chris Wolstenholme (MUSE)- Uses some great effects like a bunch of big muffs linked together... to hear that listen to Muse- Hysteria. This guy knows how to hold a song together, and thats exactly what Muse needs... with Matt fiddling with all his effects...

Also, he can play some really great things that Ive seen live, but they dont fit it in their albums because they dont mix well... For some finger tapping bass, check out Muse- Butterflies and Hurricanes.
2. Tim Commerford (Rage Against the Machine)- Of course he doesnt show off alot of skill, he has Tom Morello in the band! Tom likes minimalistic stuff, and his whammy pedal.. But Tim is a great bassist, with awesome tone (thanks to his home made pedals and pickups).