Adventures in Arda
Lord of the Rings Resources
*"Encyclopedia of Arda":http://www.glyphweb.com/arda/
System Reference Document
Contains the information from the Players Handbook in a Hypertext format
Wizards of the Coast 3.5e Archive
Contains archived web articles with rule clarifications, updates etc.
D&D Wiki SRD
Another SRD containing information that the official one may not.
Contains EVERYTHING ELSE that you may need in pdf form. Be sure to use 3.5e material.