How many (if any) songs do you know by heart? What are they?
Most of the songs on Jethro Tull albums; quite a few of those by Renaissance; at least ten songs by 10cc, especially "Rubber Bullets", "The Wall Street Shuffle", "The Worst Band in the World", "Hotel", "Une Nuit a Paris" (most of it, long song); several tunes from The Strawbs, and stuff by Thea Gilmore; some Mike Oldfield, Divinyls, and others that I have likely forgotten about but will sing with when I next hear them.
Great question, too. :)