Right now I use a 27" iMac at home almost exclusively, but there's a handful of other computers that I use in various locations, and several have persistent sessions (which makes gchat think I am available almost 24/7). It was more of a problem when I commuted every day, but I mostly just had different sets of things that I was looking at on each compy.
The Google Bookmark sync actually works pretty well between all of them for things that aren't transient. I just realized that there's probably a decent 'bookmarks sidebar' extension out there, and combined with "Open All Bookmarks in New Window" that could alleviate a lot of my project-related tabcruft.
I have indeed "lost all that state" many times over the years, but it hasn't happened since I switched to Chrome (It did corrupt its session once, but it keeps a backup). It happened every couple months with Firefox on Linux, though I couldn't dig as big of a hole since it crashed more than once per day on average.
Years ago when I used Safari as my main browser it didn't have session saving yet, I used a SIMBL extension that continuously saved all state (including the full DOM with no redownloading), but ironically caused it to crash much more frequently. In those days I would rotate between Safari, Camino, and Shiira using two at a time, so that when the primary started to fall over I could start a fresh session and let the tabs dwindle in the old ones until they could be quit.
