Monitoring the progress of fermentation of beer in a simple fashion

I wish there were a good solution to monitoring the gravity. But the more I've thought about it, I've put off trying for a solution. Most of my beer is done in 2 weeks, and I often age it for longer. It's not the kind of thing were real time information (about gravity) is super useful (IMO), because after a certain amount of time the fermentation stops anyway. I'd love it for data purposes though. I track temperature during fermentation, that's important to me.

That's pretty cool, although part of me is horrified at the thought of something else that touches the beer that I am probably not going to sanitize properly one day.