There's also a good collection of old-time tunes in MIDI format, catalogued by key. Since I last checked the site, he's added "dots" (musical notation) for the tunes in GIF and PDF format, and a collection of MIDI's for Irish and Scottish tunes as well. Very nice! Many of the tunes appear to come from the Fiddler's Fakebook, so guitarists with imperfect ears (like me!) can use that to check chords. (Yes, I know, lots of chords in that book are imperfect as well...but it's a start.)

Aloha,
Mark