Via Gary Price - Exalead, a major competitior in the 2nd tier search engines, has an incredible array of advanced operators to help sophisticated users refine queries. The offerings include:

• An advanced search page with the ability to modify virtually every aspect of keywords on/off page
• A set of advanced operators to narrow your search
• Another set that can widen your search
• A heap of cool sidebar information about categorization, related terms, etc. (a practical replacement for Teoma's resources!)

It may seem trivial, but one of the things you can do with this is search for pages by date, enabling you to find only links to a site that have been created/found in the last 10 weeks (or 10 days). When Exalead starts crawling the web deeper (and faster), expect this service to be in high demand by SEO link seekers and reverse algoers (just made that last one up).