This is still in very early development/beta stages, but I thought you guys might like to get in on the ground floor... I'm pretty sure the public betas will be free.
Site:
Tilt Demon - Stop Loss Tilt Prevention Software
Support thread:
Nov 2009 - Tilt Demon - Stop Loss Tilt Prevention, How much WOULD you have saved! - Gambling and Poker Software Forum
Basically, this software will connect to your HEM database and monitor your sessions so that, depending on how you set it, you can have it shut you down once you lose (or win!) a certain amount, exceed a certain amount of hands, or exceed a certain amount of time played. There will be lots of options to customize it, but that is the gist.
But what's more, and perhaps more importantly, there is a
free calculator on the site that will analyze your HEM database and will tell you how much money you could have saved with such a limit in place, and what your win (or loss) rate is after you exceed a certain amount lost or a certain amount of time/hands played. With a large enough sample, that could be extremely useful in determining some baseline figures to set the software too.
Even if your self-control is good enough that you don't need a piece of software to watch over you, the calculator alone is worthwhile to help you to find some of your tilt-related leaks.
I'm playing with the calculator right now; I'll post some results when I get it working.