Don't ever underestimate Kirk Hammett, for he has not only speed, but also melody. Yes, there may be a handful of guys faster than him, but none have his unique combo of speed and melody. Dream Theater's guitarist is another guy like hammett.
And yes, ever heard Blackened? Kirk Hammett is one of the greatest guitarists ever, and he is comparable to guys like Jimi Hendrix, Jimmy Page, John Paul Jones, Toni Iommi, BB King, etc.
And I am NOT a die hard metallica fan, atleast of their newer live shows anyway. Don't jump to conclutions.
And yes, one more thing: Kirk is the meaning of speed not because he is the fastest, but because he can produce melodies even at ultra high speeds.
LOL... since we're all voicing opinions, as a guitarist myself (not a very good one though) I must say "Hammet SUCKS!"
He has nothing in terms of speed, technique, melody, or anything comparable to the greats. In guitarist circles I think theres some joke about Hammet being Satch's worst pupil; second worst pupil is Slash!
You want to listen to amazing rock/metal guitars?
Joe Satriani (everything, usually slower and more melodious, but with amazing techniques)
John Petrucci (Speed and melody)
Steve Vai (crazy techniques -- look for his three-stock guitar solo)
Paul Gilbert (again speed, melody, techniques)
Reb Beach (listen to black magic)
Van Halen (for those into 80s style leads)
Yngwie Malmsteen (who is fast, but quite classical and boring at times)
Insane?
Michael Angelo Batio (double stocks like you've never seen used before)
The Great Kat (crazy classical-shred woman)
A very special mention goes to:
Jason Becker - a true guitar hero!
*en.wikipedia.org/wiki/Jason_Becker
Of course I don't expect people to agree, but here's my 2 cents worth anyway!