My wifey lost 3 hours of work last night, after typing furiously into a textarea window for a site she runs on Drupal6, clicking submit...and SERVER NOT RESPONDING...aaaarrrrggghhhh. Back-clicks didn't bring it back... everything was gone. So I awoke to one very grumpy wifey.

Super Geek to the rescue!

The following solution works ONLY if Firefox has not been closed! And Only works on Linux.

1) First, find the PID of Firefox. Do a 'ps aux | grep firefox' in command prompt, and take notice of the first number. In my case the PID was 3961.
2) Secondly, dump firefox' memory to disk with gcore: 'gcore -o dumpfile 3961'. This might take a little time; let's hope you have enough disk space.
3) Third, extract all text from the dump: 'strings dumpfile.3961 &> strings.txt'.
4) Fourth, now your text should be in strings.txt, but along with it there is a considerable amount of junk. Try to remember a keyword from the text you want to find; I looked for "Christel".
5) Check if the keyword is in strings.txt (repeat with another keyword if you get zero, remember to spell it EXACTLY right): 'grep Christel strings.txt'.
6) When you have a hit, open strings.txt in your favorite editor (could be gedit or whatever, I used geany): 'geany strings.txt'.
7) Search for the keyword again: CTRL+F Christel

I found this recipe in an archive of Ubuntu forums, and replicated it here for posterity. And because it's darn geeky. :D