RefSeek is a site that I found that is a great place to start when looking for information or links. The site's start page is just a simple listing of categories (see above).
The site has categories from dictionaries, encyclopedias, and health & medical to multimedia and teacher resources. When you click on a category, you are brought to another page that has a list of web sites and descriptions of them. There are some great resources for each category.
The site is in Beta and doesn't have a huge number of resources for each category, but it is a great starting point when you are looking for resources.