Must Have Songs at a Wedding Reception

Hey everyone!

When you do to a wedding are there any songs that you hope to hear? Any songs that you don't want to hear? What are the must be heard songs?

I am in the midst of planning my wedding in September, and we have decided to forgo the DJ and make a wedding playlist on Itunes and hook it up to a PA system. We're having a small and intimate wedding of only 45 so we figure it will work out well; plus we'll save over $800.