Still my favourite browser by far. I usually have 3-4 windows open and up to several hundred tabs and Firefox handles this better than anything else.
The unfinished reading weighs me down every day, but I keep them open anyway. Some days I get productive and read a half dozen tabs, but never anything substantial. It's an embarrassing "problem."
Awesome / useless plugin idea: an artificial time bomb that removes the tab and all traces of the website from your history after being open longer than some period of time (e.g. one week). Obviously a bookmark circumvents this dilemma, but the problem itself isn't rational to begin with.