Search Engines

BoardReader
Searches a variety of message boards and forums in 14 different categories.
http://www.boardreader.com/

BoardTracker
Searches a wide variety of forums organized by category, includes email or IM alert capability. Basic functions are free, advanced ones require paid plan.
http://www.boardtracker.com/

Phaster: Search Discussion Boards
Search a selection of discussion groups including All Experts, Weblog Hop and Google Groups.
http://www.phaster.com/find_info_deja.html