Here we go with a great little add-in for your FireFox browser: Alexa Sparky. Now you can see Alexa ranking data in your status bar, for your site, and every site you visit on the ‘Net! No more having to trot over to Alexa.com to check your (or anyone else’s) popularity rank.
Written by Alexa, this add-on also provides a right-click menu full of handy links that:

show how this site’s traffic compares to other sites’ traffic
shows you other sites like the one you’re on with Related Links
tells you whether this site …

Well, for starters, the 3 reasons on the FireFox homepage have been true for me:

it’s faster
it’s more secure
it’s fully customizable

Given that I spend hours and hours online every day, all three of those reasons are extremely important to me.
Other reasons are: