Firefox Extension Heaven

For people who have "slightly more than one computer", keeping your bookmarks up to date on all the boxes can be a major pain. I try to stick with a "minimal number of machines" myself:

1). Main Thinkpad Laptop - 50% of total work here, goes with me most places.
2). Main Home Desktop - Current location, some work, some home, photos, music, critical machine.
3). Mac - Video editing, iTunes, iPhoto ... a must have.
4). Backup Desktop at work, dual boot to Linux - Laptops die on occasion. Can't be sitting still then. At other times, technical currency on Linux.
5,6 and 7 ... One new IBM re-furbished 1.8GHZ that just followed me home for $150. 2 machines that used to be my sons but are now running some grid computing stuff, keeping disks spinning for stored video, and available should any of my relatives need a newer machine. These 3 might be slightly less easy to justify than the "critical 4".

I'm slightly embarrassed to not currently have a Linux box up and running at home. I plan to remedy that shortly with an ubuntu installation that I have high hopes for.

On to the heavenly extension
Google Sync which allows you to keep your bookmarks up to date between as many computers as you want, and even better have the browser re-configure to your latest tabs / pages when you switch machines. SWEEET!! So far working flawlessly and I'm very impressed and appreciative.

Now if I can just find "the same thing" for Thunderbird.