Where is fun to visit in Central America?

I will be visiting Belize in June to work on the coral reef and in the rainforest. After this I intend to travel for 3 or 4 weeks on a budget. I would like suggestions of where to visit whilst I'm there and information about budget accomodation.

Been to most of C.A. and Honduras is my #1 choice, with Belize and Costa Rica tied at a close second. I found the nicest place on the mainland of Honduras was Tela. It's a small city right on the north coast, very local and non-American but very friendly. I enjoy the local scene more than the tourist scene. Hope you find a place you love!