I'm an electronics engineer, and founder of a small company that makes scientific imaging cameras. That grew out of a personal interest in astronomy - got interested in the instrumentation and started making stuff. I have co-discovered 12 supernovas and 1 comet.
For letting off steam, I'm into racing cars. My current racecar is a Radical SR3 RS, which I run in some Canadian race series. I also do endurance racing in Lucky Dog series in Canada, and also the ChampCar series at US tracks. I'm a "pay driver", because I just buy a seat for the weekend. That said there are a couple of teams that I usually run with. These are typically 8 hour races with 2 hour stints, pit stops for refueling and driver changes, etc. I've done a couple of 24 hour races at VIR. If you've ever watched Le Mans it's pretty much the exact same thing but in much slower and cheaper cars LOL.
Here's a pic of my car:
