QUOTE(eirlys @ Dec 4 2008, 03:31 PM)

I was going to suggest 'I Know Him So Well', that was popular at my school around GCSEs. I also remember someone doing Rossini's Cat Duet.
For something more recent how about 'What Is This Feeling' from Wicked? The beginning part of 'Defying Gravity' has some beautiful harmonies too, but of course it's much more Elphaba's song so no good if both are being assessed.
One for male/female would be 'A Little Fall Of Rain' from Les Mis, that is a beautiful song.
If you're going for Wicked, For Good is a really nice duet - but there are long sections with very little harmony, and all the harmony comes at the end. I love it though.
Take Me Or Leave Me, from Rent is good. I like it anyway...
Marry the Man Today from Guys and Dolls is really funny, or there's "Sisters" from White Christmas (I think?).
Those are only musical theatre ones though. I second, or third the suggestion of I Know Him So Well too.