AdSense isn't the only way to make money! How about these:
1. Offer tabsheets that you've created yourself, along with
lyrics that you've transcribed and even your own personal tips
for playing the song and effecting the artist's style.
Perhaps packs of 10-15 tabsheets, maybe grouped by artist,
genre, album and so on. $12-18 per pack?
2. Offer video tutorials, teaching your visitors how to play the
guitar. Have several different guides going over different music
styles, techniques, perhaps even a step by step "how to play
this song" to be bundled with a tabsheet from 1?
3. A classifieds section to let your users buy and sell second hand
musical equipment.
4. Become an affiliate for a gig ticket seller, offering tickets to gigs
featuring lots of guitar music.
5. And so on...
Don't rely on PPC - if AdSense bans you, there's no going back.
PS - shameless plug: for more ideas to get your creative juices
flowing, check out
http://BrightIdeas-Mag.com 