Visiting the 10 top sites in a category will give you a good overview of that field. This crowded but useful site is a designed as a teaching tool about how to search the Internet. It's meant to be used by both librarians and non-librarians as a reliable and efficient guide to described and evaluated Internet resources. The site is maintained by librarian Carol Leita who also publishes a weekly newsletter outlining the top 20 sites added to the resource each week. ODP relies on a vast army of volunteer editors.
People sign up as editors of topics they know something about and then review sites in that area.
It is a self-regulating community where editors' contributions are rated by other users in forum discussions. An automated link checker scrubs expired links off the directory. ODP has become an important source for Yahoo and other major search engines, so it is important to have your site listed here. I've been told I resemble my Yellow Lab, Sam. I consider that a compliment.