The best spot for these lists though is DigitalDreamDoor. They update with new votes about once a month. Their current top 25s
Guitarist:
1. Jimi Hendrix* - Jimi Hendrix Experience
2. Eric Clapton - Yardbirds, Cream, Derek & The Dominos, Solo
3. Jimmy Page - Yardbirds, Led Zeppelin, The Firm
4. Jeff Beck - Yardbirds, Jeff Beck Group, Solo
5. Eddie Van Halen - Van Halen
6. Stevie Ray Vaughan* - Stevie Ray Vaughan & Double Trouble
7. Joe Satriani - Solo, Rainbow
8. Ritchie Blackmore - Deep Purple, Rainbow, Blackmores Night
9. Steve Vai - David Lee Roth, Whitesnake, Solo
10. David Gilmour - Pink Floyd, Solo
11. John Petrucci - Dream Theater, Liquid Tension Experiment
12. Randy Rhoads* - Quiet Riot, Ozzy
13. Allan Holdsworth - Solo
14. Paul Gilbert - Mr. Big, Racer X, Solo
15. Yngwie Malmsteen - Rising Force, Solo
16. Phil Keaggy - Glass Harp, Solo
17. Jason Becker - Cacophony, David Lee Roth Band, Solo
18. John Mclaughlin- Mahavishnu Orchestra
19. Duane Allman* - Allman Brothers Band, Derek & the Dominos
20. Chuck Berry - Solo
21. Eric Johnson - Solo
22. Steve Howe - Yes, Solo
23. Neal Schon - Santana, Journey, Solo
24. Brian May - Queen
25. Gary Moore - Thin Lizzy, Colosseum II, Skid Row, Solo
Bassist:
1. James Jamerson (Funk Brothers, session man)
2. John Entwistle (The Who)
3. Larry Graham (Sly & The Family Stone)
4. Chris Squire (Yes)
5. Jack Bruce (Cream)
6. Tony Levin (King Crimson, session man)
7. Geddy Lee (Rush)
8. Paul McCartney (The Beatles)
9. Louis Johnson (Brothers Johnson, session man)
10. Anthony Jackson (session man)
11. Flea (Red Hot Chili Peppers)
12. Marcus Miller (session man)
13. Les Claypool (Primus)
14. Chuck Rainey (session man)
15. Billy Sheehan (Niacin, Mr. Big, Steve Vai)
16. Geezer Butler (Black Sabbath)
17. Will Lee (session man)
18. Michael Manring (Attention Deficit, session man)
19. Nathan East (Eric Clapton, session man)
20. Rocco Prestia (Tower Of Power)
21. John Paul Jones (Led Zeppelin)
22. Abe Laboriel (session man)
23. Stuart Hamm (Joe Satriani)
24. Donald "Duck" Dunn (The MGs)
25. Dave LaRue (Dixie Dregs)
Male Vocalist/Frontman:
1. Mick Jagger (Rolling Stones)
2. Chuck Berry
3. James Brown
4. Freddie Mercury (Queen)
5. Elvis Presley
6. Tina Turner
7. Jim Morrison (The Doors)
8. Iggy Pop (The Stooges)
9. Bruce Springsteen
10. Steven Tyler (Aerosmith)
11. David Lee Roth (Van Halen)
12. Roger Daltrey (The Who)
13. Little Richard
14. David Bowie
15. Jimi Hendrix
16. Joey Ramone (The Ramones)
17. Scott Weiland (Stone Temple Pilots/Velvet Revolver)
18. Bruce Dickinson (Iron Maiden)
19. Maynard James Keenan (Tool, APC)
20. Eddie Vedder (Pearl Jam)
21. Zack De La Rocha (Rage Against The Machine)
22. Ozzy Osbourne (Black Sabbath)
23. Bono (U2)
24. Corey Taylor (Slipknot, Stone Sour)
25. Ronnie Van Zant (Lynyrd Skynyrd)
Drummer:
1. Neil Peart (Rush)
2. John Bonham* (Led Zeppelin)
3. Carl Palmer (ELP)
4. Keith Moon* (The Who)
5. Terry Bozzio (Frank Zappa)
6. Ginger Baker (Cream)
7. Hal Blaine (Session man)
8. Danny Carey (Tool)
9. Bill Bruford (Yes, King Crimson)
10. Earl Palmer (Session man)
11. Mike Portnoy (Dream Theater)
12. Dave Lombardo (Slayer)
13. Benny Benjamin* (Funk Brothers)
14. Ian Paice (Deep Purple)
15. Carmine Appice (Vanilla Fudge)
16. Tommy Aldridge (Ozzy Osbourne)
17. Stewart Copeland (The Police)
18. Bernard Purdie (Session)
19. Vinnie Colaiuta (Zappa)
20. Jeff Porcaro* (Toto)
21. Bill Ward (Black Sabbath)
22. David Garabaldi (Tower Of Power)
23. Ainsley Dunbar (Jeff Beck)
24. Nicko McBrain (Iron Maiden)
25. Mike Shrieve (Santana)
Female Vocalist:
1. Janis Joplin
2. Grace Slick (Jefferson Airplane)
3. Ann Wilson (Heart)
4. Stevie Nicks (Fleetwood Mac)
5. Tina Turner
6. Pat Benatar
7. Debbie Harry (Blondie)
8. Annie Lennox (Eurythmics)
9. Kim Gordon (Sonic Youth)
10. Joni Mitchell
11. Chrissie Hynde (The Pretenders)
12. Patti Smith
13. Melissa Etheridge
14. Bjork
15. Nico (Velevet Underground)
16. Alanis Morrisette
17. P. J. Harvey
18. Kate Bush
19. Tarja Turunen (Nightwish)
20. Ani Difranco
21. Delores O'Riordan (Cranberries)
22. Shirley Manson (Garbage)
23. Patty Smyth (Scandal)
24. Rickie Lee Jones
25. Sandy Denny
And the one poll we don't have yet:
Keyboardist:
1. Keith Emerson (ELP)
2. Rick Wakeman (Yes)
3. Jon Lord (Deep Purple)
4. Ray Manzarek (The Doors)
5. Richard Wright (Pink Floyd)
6. Tony Banks (Genesis)
7. Billy Preston
8. Ian Underwood (The Mothers Of Invention)
9. Steve Winwood (Traffic)
10. Nicky Hopkins (Rolling Stones, Jeff Beck)
11. Al Kooper (Blood Sweat & Tears)
12. Jordan Rudess (Dream Theater, The Dregs)
13. Tony Hymas (Jeff Beck)
14. Gregg Allman (Allman Brothers Band)
15. Booker T. Jones
16. Jan Hammer
17. Kevin Moore (Dream Theater)
18. Gregg Rolie (Santana, Journey)
19. Brian Eno
20. T. Lavitz (The Dregs)
21. Richard Tandy (ELO)
22. Dennis De Young (Styx)
23. Jens Johansen (Yngwie Malmsteen)
24. Kerry Livgren (Kansas)
25. Rod Argent (Zombies, Argent)