One of the slick visual elements of Google's Chrome browser is pin tabs. They're those compact tabs that're only as wide as a favicon, and they save a ton of space in your tab bar. You could point out that Firefox doesn't have this feature, but I'd give you the Firefox fanatic's standard answer: there's an add-on for that! For Chrome-style mini-tabs in Firefox, grab the Pin Tab extension.

Pinning a tab using ctrl-click shrinks it and moves it to the left of your tab bar. A pinned tab is preserved across all sessions, and you can't accidentally upset it using the address bar. If you enter a new URL while a pinned tab is selected, that URL opens in a new tab instead. You can pin tabs by dragging them to the left of the tab bar, and unpin them by dragging them to the right. Pinned tabs save a ton of space, since they're several times smaller than regular ones, so this add-on is ideal for those who have dozens of sites open at once.

[via gHacks]

UPDATE: The developer of this add-on seems to have taken it down for right now.