Nomadic Matt’s Travel Site has an excellent post titled Seven Things to Do in Iceland (Why You Should Go Right Now!).
As a group of us are getting together to go there this Easter, this is a nice place to quickly read up on Iceland if you are interested in joining us. Keep in mind that while the tickets and hotels are still very cheap, they tend to run out sooner or later, and you can already see the prices rise on a daily basis.
Gallery: Seven things to Do in Iceland
Worth adding is also Whale Safari, where a large number of different whales are often sighted all around the Icelandic coast.