Jere Haakana, an unknown but still great guitarist, plays a 7 string, and he has some great/psycho songs. Check out his page at http://personal.inet.fi/surf/jerehaakana/index.htm

Also, you can download some of his songs from MP3.com at http://artists.mp3s.com/artists/53/jere_haakana.html

He has done some lessons specifically for 7 string guitar at http://www.chopsfromhell.com
You can find these at http://www.chopsfromhell.com/guest_haakana.html
This first lesson includes an extensive look at Jere's slap+pop guitar technique. It also has a little section on two handed tapping.

And the other one is at http://www.chopsfromhell.com/guest_haakana2.html
This one includes: heavy riffs, 7 string sweeps, his awesome slap+pop technique for guitar, crazy string skipping scales, and two-handed piano-like technique (tapping an arpeggiated chord in the left hand, and a chord fragment or melody an octave or two up with the right hand, implying chords like a piano player would)

You should email Jere (there's a link on his homepage) and ask for permission to put those lessons he wrote on your new 7-string guitar lessons page. Hope this helps...