Obviously there's a lot of category overlap, but that's life for you. I haven't put in very many links yet, but I don't really have to, because any site in a particular category will contain so many links itself that to find one is usually to find them all. If you want more, then try using an index like Yahoo or a search engine like Altavista.
More categories will be added later, as you might imagine, but here's a start: