Yahoo has been running a public beta for a while that lets you explore a domain or webpage, called Yahoo SiteExplorer. I always thought this to be a very useful tool in finding out some info on my websites. It generated a summarized list of other websites linking to me.
I just noticed that Google has recently included a similar service in the Webmaster section. In the past they didn’t release much information on who is linking to you. This new tool was actually released on February 5th as I read on Matt Cutts blog today. I was actually pleasantly surprised that the Webmaster Tools gave a better indication then the “link:www.domain.com” version in the search engine.
Granted it probably is still hiding most of the inlinks Google is counting in their algorithm, but it helps getting an indication of how your website is doing.