GURPS Advantages, Disadvantages and Skills: Collection of alphabetical listings of official Ads, Disads & Skills appearing in all published GURPS sources through November 1998.
GURPS Worldbook Index: Complete index of every GURPS book ever published.
Index of Official GURPS Errata: An index of errata maintained by Steve Jackson Games. Includes every GURPS book ever printed, sorted by printing and edition.
The GURPS Library: Rated - A Consumer's Guide: Game designer S. John Ross rates the quality of each book in the GURPS library.