Ok, this one is not really bouzouki-ish, but if you play GDAE you can use it as it is. Nigel Gatherer's Traditional Music Pages is a fine site containing lots of tunes for Mandolin, Whistle or mixed instruments. You'll find Scottish and Irish tunes there in ABC and Mandolin tab. If you play GDAD like me you have to work a little bit on the tunes. But nevertheless this one's a good plays for finding good tunes. Look at this great website and decide for yourself.