logKext keylogger
One my family members seems to lose her work distressingly often, particularly long blog posts she composes in browser windows which then crash. In trying to think up a solution to this problem I hit on the idea of using a keylogger that would record all of her keystrokes, and thus allow me to recover the text. I found just such a program-a freeware kernel extension called logKext. The kernel extension loads at startup and you can access the keylog through a terminal based client, which will write the keylog to your desktop as a text file. What I discovered, however, is that this is not a terribly useful way to recover text, precisely because folks rarely type straight through, rather we often hit backspace or delete to make corrections. So when you look at the keylog you'll find a huge number of s, etc. Nonetheless, in a pinch it will bring back text, and if you were truly serious about it, you could probably run the keylog text through a text factory or similar text processing methodology to automatically remove the 's, etc. As a far more practical solution, I convinced her to stop composing in a browser, but in a text editor with auto-save, and then to cut and paste into the browser after she's finished (though now I'm thinking of getting her going in MarsEdit).
Of course a keylogger can be used for much more nefarious activities (and it is not really detectable in normal operation unless you know it's there), but I pass over those in silence. The logKext keylogger is a free download from FSB Software.