http://sherlockhoward.homestead.com/SherlockHolmes.html

I've only just stumbled onto it, so I don't know what's deeper in, but the first page is a delight!

http://www.schoolandholmes.com/index.html

This index of the published pastiches also includes summaries, a handy dandy American to British glossary, a list of the unpublished cases and... well, you get the idea. Go explore!