Does anyone have/know of any good vocal duets with piano accompaniments?

Because me and my friend want to sing a duet (with harmonies)....she's a Mezzo-soprano (or a soprano, not sure) and I'm an alto...and we prefer pretty and slow songs as opposed to rock!!! :D

Any idea's or links would be very much appreciated....

Laura
XxX

I have a piece that you might be interested in on my website. Its called Uguisu, and it's for soprano and alto with piano accompanyment. its about 3minuts long and it's in Japanese. you can get the sheet music at mattgreenecomposer.com