There are a lot of SEO (Search Engine Optimizers) extensions out there to help you write the best post for your site. In my eyes, you can't have enough extensions to help with Search Engine Results.
SearchStatus is a fundamental statistic extension for determining the best keywords, keyword density, show meta tags, and other SEO functions that are truly helpful.
When you install the extension and restart Firefox, you'll notice the icon in your status bar looks similar to an "at" symbol (@), but contains a "q" instead of an "a." Left-clicking will get you nowhere, but right-clicking displays your menu.
The first thing that drew my attention was the "Enable PageRank" and "Enable Alexa Rank." Here's a quote from their site.
For every web page you visit while using SearchStatus (excluding secure domains and those you have configured as private), certain information, including your ip address, the url of the web page you visit, and general information about your browser and computer's operating system will be transmitted from your computer to Alexa. Some of the url's you visit, which are transmitted to Alexa, will contain information that is personally identifiable.
Hmmm...Nothing like helping someone's site stats out on Google or Alexa. ;-)
The one cool feature I did pay particular attention to was the Keyword Density. Enter in a keyword and it will scan the current web page for that keyword and tell you the percentage where it's used the most.
The one drawback to that was that after I did a keyword density option, I walked out of the room for an hour and left the dialog box on the screen. When I came back later, I didn't know what keyword I entered. Minor cosmetic flaw, but easily fixed by adding it to the caption.
The SearchStatus extension also provides the indexed and backward links for Google, Yahoo!, and MSN. Very nice feature as well.
As I said before, you can never have too much help when it comes to SEO for your web site or you examining a client's web site for rank-ability.