Ancestry.com - Ancestry tree and social security death index. Most databases are for paying members.
Cyndi’s List of Genealogy Sites on the Internet - More than 55,150 links.
Family History.com - Message boards for genealogical research.
Family Search Genealogy Service - Sponsored by the Church of Jesus Christ of Latter Day Saints and searches the International Genealogical Index and the Ancestral File Pedigree Resource File.
RootsWeb.com - Free genealogical data, ship lists of immigrants.
The USGenWeb Project - Provides links to census info, marriage bonds, wills and other public documents, state and county pages, the tombstone project, tips on how to get started in genealogical research and the USGenWeb Digital Library.
WorldGenWeb - Provides free access to genealogical info by anyone in the world. Goal is to have every country represented by an online website.