Customise the way Facebook looks on your browser

I was recently searching for ways to customise my Facebook profile and have found that most of the CSS hacks (etc) have been disabled to keep Facebook layouts uniform across all profiles.

There is, however, a Firefox Addon called "Boost" by StudioLD which allows you to customise the appearance of Facebook client-side, which means that it will appear differently in your browser only. It also adds some useful features, such as a feature that expands thumbnails when you roll over them, and also allows you to auto-login, avoiding the need to login to Facebook multiple times in a single session.