Nathan points to Omgili a search engine for web-based discussion forums.
From the Omgili web site…
Omgili is a search engine designed specifically to analyze web-based discussion forums. While Google has a Usenet-based search engine, it neglects the tremendously popular and information rich web-based discussion forums.
Many individuals who use Google’s Usenet search engine understand there is a wealth of information contained in such discussions. Often times, this information is more valuable than information contained in ordinary web pages.
However, the growing popularity of web-based user forums has eclipsed that of Usenet-based discussion threads. Nevertheless, this web-based information remains either unobtainable or disorganized from Google searches. This is where Omgili comes into play.
“Omgili only indexes the information found in web-based discussion forums,” says Ran Geva. “Although Google.com is a tremendous resource, in many cases your search query is muddled with irrelevant search results. By only indexing discussion forums, all unnecessary information is avoided, giving you the results you want.”