The top 20 riffs:

1. Sweet Child O' Mine - Guns N' Roses
2. Smells Like Teen Spirit - Nirvana
3. Whole Lotta Love - Led Zeppelin
4. Smoke On The Water - Deep Purple
5. Enter Sandman - Metallica
6. Layla - Derek & The Dominoes/Eric Clapton
7. Master Of Puppets - Metallica
8. Back In Black - AC/DC
9. Voodoo Chile (Slight Return) - Jimi Hendrix
10. Paranoid - Black Sabbath
11. Crazy Train - Ozzy Osbourne
12. All Right Now - Free
13. Plug In Baby - Muse
14. Black Dog - Led Zeppelin
15. Ain't Talkin' 'Bout Love - Van Halen
16. Walk This Way - Aerosmith w Run DMC
17. Sunshine Of Your Love - Cream
18. No-One Knows - Queens Of The Stone Age
19. Paradise City - Guns N' Roses
20. Killing In The Name - Rage Against The Machine
http://news.bbc.co.uk/2/hi/entertainment/3677965.stm