SessionSaver Firefox Extension
Have you been in a situation where Firefox crashed and you lost track of all the tabs that were opened, important ones and you have to fiddle back to your brain to remember them. SessionSaver is a Firefox Extension that saves your last session, you can even have it restored everytime Firefox starts.
It even claims to save windows, tabs, even things you were typing (I haven’t experienced this part of the fun).
Read more details about SessionSaver.