If you have a lot of tabs open, the ability to bookmark tabs and jump directly to them, as well as to the previously active tab, will save you a lot of time. This extension does that.
I personally make GMail #1, music streaming (beastmode.fm) #2, Netflix #3 and quickly bounce between them and 50 other tabs.
[Updated 1/26/12 to work across multiple windows]
Extore is a team of professionals who are passionate about creating extensions for web browsers. This devotion also gives us opportunity to appreciate work of other people. We get inspired by useful, open source extensions made by developers all over the world. Our strong belief is that one should share helpful add-ons with others. That’s why we’d like to present you our ever-growing list of favourite extensions that have inspired us. Moreover, as you probably have already learned, sometimes struggling for the best brings an end to the good. Talking about add-ons it often turns out that an upgrade is worse then previous version. Also it can become really tricky to get back to the beloved version of your favourite extension. That’s why we’re going to make not only the latest, but all versions of our favourite (and we hope yours too) add-ons available for download. No more compromises, just stick to the version you really like!