I see Eric Johnson lists his Top 10 Guitar Tones of all time on the MR homepage. Pah, what does he know, I saw him live recently and his tone wasn't all that!
So what's yours? (lets keep it to 5 to make it harder to choose and easier to read).
I'll start: in no particular order and with little thinking time...
Neil Young - Cortez the Killer (live Weld version)
Eric Johnson - Cliffs of Dover (I'll give him that, spent a good protion of my yoof trying to relicate)
Jimi Hendrix - Bold as Love (that fuzz tone at the end, yummy)
Larry Carlton - Kid Charlemange
EVH - Beat It
Thinks that covers it, although just to cheat and on a more general basis: anything by Peter Green or Jeff Beck, them boyz haz da toan IMO.
1) Stevie Ray Vaughan on Mary Had A Little Lamb from Montreux (Lipstick tube pickups!), especially the vibrato on the 12 fret at 0:31
2) Allan Holdsworth on Non-brewed Condiment from Then! live in Tokyo - liquid, thick, fat yet spiky
3) Gary Moore on Oh Pretty Woman - the loudest-sounding guitar recording ever achieved
4) David Gilmour on Comfortably Numb - the live Pulse tone just edges it for me
5) Walter Trout on Going Down from Live No More Fish Jokes. First chorus of his solo at about 3:30 where he's on the edge of feedback the whole time. Similar at the end of She's missing from the Transition album but couldn't find it on youtube
Robben Ford - "Help the poor" and "Talk to your daughter" (same album)
Steve Lukather - the solo from Olivia Newton John's "Physical" (don't laugh) and Chicago's "Hard to say I'm sorry"
Larry Carlton - "Kid Charlemagne"
Jay Graydon - Anything
Nile Rodgers - Anything! Ok, "Thinking of you"
Michael Thompson (sessioner) - His "LA Clean Tone"