As much as I like Google Chrome, this is the type of trick that keeps me using Firefox as my day to day browser.

I use Google Apps for my domain and so I visit my calendar and gmail quite a few times a day. I've tried various ways to make this easier with bookmarks, the Awesome Bar in firefox, etc. However, I just like having tabs open for these apps for the fastest access. Unfortunately, this leads to a fair bit of screen real estate taken up with these tabs. That's where FaviconizeTab comes in handy. It makes the tab only show the little favicon that many sites show in the address bar. Since I pretty much always want tabs open for gmail and gcal, I can make the permanent with the PermaTabs extension.

For those "want them open sometimes, but not always apps" like Facebook and Pandora, I can open them and faviconize them and scoot them over with the permatabs.

it's a simple little trick, but makes Firefox just a teeny bit more useful.