With two computers and a dotmac account, I've been happliy syncing up my Apple software like Mail, Safari, Address Book and Calendar. Syncing works with my copy of Transmit too! But that's because the Transmit developers are on top of things.
So, when Google announced
Browser Sync for Firefox, I was elated! My PowerBook has a more complete set of bookmarks than my desktop computer.
There is one caveat that you should be aware of before installing and syncing up more than one computer, if you choose try Browser Sync out. The syncing process does not take into account the bookmarks and settings that are the same from one computer to another. So, you'll end up with duplicated bookmarks and such.
One way around this is to choose whichever copy of Firefox has the best seletion of bookmarks and use that as the target set. Then before updating a second computer, go into Firefox bookmarks and remove them.
I deleted the whole set of bookmarks on one computer and then ran Browser Sync. Now I have the exact set of bookmarks on both computers!