SearchStatus displays following information:
no-follow links (very important feature)
Google Page Rank
Alexa Ranking
Meta-Tag information
Robotos.txt
Whois
Keyword density
by Search Engines indexed pages
Backlinks

SEO for firefox shows near results of search request in a search engine:

Goole PageRank
How old is the site
Quantity of bookmarks of this site on del.icio.us
Backlinks from sites in Yahoo index
Backlinks from edu sites in Yahoo index
Backlinks from gov sites in Yahoo index
Backlinks from sites in Yahoo index, which linked a page from search result
Backlinks from edu sites in Yahoo index, which linked a page from search result
Links from Technorati
Alexa Ranking
Quantity of pages cached by Google
DMOZ information
Quantity of people, who are subscribed for RSS-feed on Bloglines
Quantity of posts in Yahoo directory
Backlinks from sites in MSN index
Backlinks from edu sites in MSN index
Backlinks from gov sites in MSN index
Whois

User Agent Switcher offers a possibility to change quick and easy user agent of your browser,
so you can test a sites for a cloacking.

Future PageRank

If you notice that PageRank of your site is “jumping”, than it is a high probability that Google makes PageRank update. There are many free tools to check PR of your site on many data centres. With this information you can suppose your future PageRank. For example this one:

http://www.seochat.com/seo-tools/future-pagerank/