hey, my school has an "acoustic cafe" every year where students can play whatever they want to showcase their talents. I was wondering what are some great songs to play on the piano while singing? I`m a pretty advanced piano player so any idea is welcome. and could u guys send me the sheet music if u have it?

also, what are some good songs that have piano and guitar with harmonies (i want to do a duet with my friend too)...thanx guys! ^__^