[maxerickson]

What platform? On XP, I leave a firefox session running for weeks and it only gets up towards 1 gigabyte (seems even less with some recent updates, but I don't keep a close eye on it).

I leave gmail and lots of other tabs open all the time.

(Mostly I suspect they are better able to find the leaks on Windows, no idea why that would be)

[com2kid]

I have seen JS webapps that leak memory something awful. I have never encountered anything as bad as the grandparent post, but a gig or two of growth after a week of just one tab open containing one misbehaved web app is not unheard of.