Right now I have about 200 open, it usually doesn't get up that high. 50 or so might be normal at any given time. I usually keep opening new tabs until Firefox crashes... though these tabs can accumulate over the course of a day or two. It sounds bad, but it works out.
Never got up to 200. I have 47 open right now. I have had a lot more in the past.
I am using Opera, not Firefox, so I have never had a problem with crashing.
Accept the past. Live for the present. Look forward to the future. Robot Fusion
"As our island of knowledge grows, so does the shore of our ignorance." John Wheeler
"[A] scientist looking at nonscientific problems is just as dumb as the next guy." Richard Feynman
"[P]etabytes of  data is not the same thing as understanding emergent mechanisms and structures." Jim Crutchfield
I have 3 browser windows open with respectively 5, 5 and 6 tabs open in them, semi-arranged by theme. I restarted my laptop a couple of hours ago, in a few days I'll probably have 6-7 open windows with 4-6 open tabs in each.