Family Search --The LDS Library site. Has some good "getting started" information as well as things to search. LDS Library has THE largest collection
of family history records and documents.
Ancestry --Has a great search feature and plenty of "non-member" available information.
Gendex Good place to find out if others are researching your same tree.
US Gen Web Project Good way to find information about a specific County that might not be listed else where.
Social Security Death Index -- Don't forget when searching the SSDI that only those whom a living relative
requested benefit from deceased ss will be listed here.