Using firefox browser which comes with my Fedora 5 installation, after some time, lets see how much it can "eat" your computer memory: it have 8 opened tabs, from which only one is "complex" (gmail.com)
$ ps axu | grep firefox mator 2823 1.7 37.3 796336 383508 ? Sl Aug18 102:07 /usr/lib/firefox-188.8.131.52/firefox-bin
so, after 4 days of running it taken 800Mb !!! A good way to make firefox to eat all memory is to leave it in memory for 2-3 days with some pages which auto-reload, like gmail, nagios service tracking or some news site.
Ofcourse this can be fixed by closing firefox and running it again, but first i need to bookmark all tabs, close it, and run it again, choosing from bookmark menu to open all tabs. I so much missing of opera functionality, storing all open tabs itself and asking for opening it on next run by default.