The Lurker's Guide to Babylon 5 is the best B5 resource on the Web.
To learn about Oz on the Web, you should go straight to the home of all things Ozzy--The International Wizard of Oz Club, Inc.
The Nitpicker Central Internet Extension Office (the NCIEO) is the place to go to find out the latest in nitpicking, straight from the author of the Nitpicker's Guides, Phil Farrand.
And the coolest store I have ever entered (and now have toured!): Hammond Ashley.