http://www.brickset.com/
That site has basically every lego set. Just look in the themed section, and you'll find what you want. I really wish I had pirate and space sets. The space sets worth getting are probably Blacktron 1 and 2, Exploriens, Ice Planet, MTron, Space Police 1 and 2, and Unitron. Those would be great to get. My cousin, who is 4 years older than me, used to make his own sets out of the Space Police 2 and Mtron sets, and they were really cool. Those legs are very versatile.