If you look for photo agencies, you'll find any of them will give guidelines for what type of photography they accept - but be advised, they have very strict criteria - they expect a very high professional technical standard.
I believe you can sell them for a lot on istockphoto. You need to submit portofolio first and wait for the acceptance.
You could use at least a dozen of methods to sell your photos. You could use Flickr to sell photos or you could sign up to websites that help you sell them like shutterpoint. Setting up a blog to promote and showcase your photos is a must, posting to forums in the relevant sections is yet another thing you could employ. Google some stuff and dig up in forums and you will get plenty of ideas. Hope this helps! Best of luck!
Place to sell http://www.fanartreview.com http://www.photosociety.eu http://www.zibbet.com http://www.citizenside.com
Some folks already mentioned istockphoto...just Google "stock photos" or "selling stock photos"and you'll see lots of similar results.