Firefox Productivity Addons

I do a lot of web development and I frequently find myself with 20+ open tabs. I use a lot of addons to manage this and to make my firefox usage more efficient: Aging tabs, sxipper, fire gesture, foxmarks, next tab, a few other minor addons that give minor productivity boosts and a whole suite of web dev/design tools on top of that.(checkbox mate is pretty nice if you haven't seen it) I'm about to try out tabkit and fisheye tabs to see if they help me at all. But the addon that I really want and need doesn't seem to exist.

I work on a laptop, a work computer and a home computer. When I switch computers I frequently need to open the 20+ tabs that were open on the other computer. I have been passing around a text document full of URLs with dropbox but that is an awful and time consuming solution. Not to mention I lose sessions/cookies when I transfer over(though that would be a much more difficult addon from a developer perspective then what I am looking for). What I want is basically a foxmarks for my open tabs, and as far as I can tell this doesn't exist at all. I just grabbed Send Tab URL's, which will make my life slightly easier, but it is not truly what I am looking for.

I would definitely be willing to pay for such an addon, though I have never really heard of addons costing money. But if there was an addon like that that saved sessions and cookies across computers, people would definitely be willing to pay for it.