Dancing Queen, Voulez-Vous, Waterloo? Classics! Plus any song that you can dance to like and idiot is awesome in my book. We saw Mamma Mia! for my birthday yesterday and I loved it - with two exceptions.
1) I think Meryl Streep was a bit old for the part
2) Peirce Brosan can not sing. Tricia and I actually cringed when we realized there was a second verse to his song. YIKES!
So I have just purchased the Broadway soundtrack instead. That was I get all the songs (plus some) and I never have to here PB sing again! Well until the winter when I buy the DVD.