The following is a paid review for ReviewMe.
SEO for Firefox is a little plug-in for search engine optimizers (optimizators?) that ammends Google and Yahoo search results will all sorts of related trivia on sites that show up in the search results. This will give you an idea why certain site is ranked higher up than others for a particular search term. To give an example you guys can relate to: if you search for "advertising blog", these three come up at the top: Adverblog, Adrants and Adland (I was pleasantly surprised to learn that Ad Lab is #4).
If you turn the plug-in on, you'll find out that Steve Hall's site trails Martina's even though AdRants has a higher page rank and beats Adverblog in just about any other indicator. To figure out what's going on, you'll either have to use many of the other tools the site makes available or contract professional SEO services the site promotes.
In other words, the tool is nifty but does not paint a complete picture, although I like how it gives the number of del.icio.us and Bloglines links. The age is off by one year, but that's because the plug-in pulls its data from archive.org. The coolest of all other goodies is this typo generator, an essential tool for any business, cybersquatting or otherwise.