I'm particularly fond of archaeologically important sites, so places like Egypt, Pompeii, and Petra, among others, have always been on my dream list; I've yet to visit any of them.

Right now, however, I'd have to say that my top ones would be Iceland and Tunisia. I've read quite a bit on Iceland and everything there, from the culture to the landscape, utterly fascinates me. Tunisia is similar, just because it's been influenced by so many different cultures (French, Roman, Byzantine, Arab, etc) over the centuries. Hopefully I'll be on my way to one of these two before the end of this year.