Realtime telemetry for race and street cars. Open source firmware, hardware and mobile app. https://github.com/autosportlabs . Our tech is used by many people, from car enthusiasts, to professional race teams to even race boats that go nearly 200mph.
I focus mainly on the website and telemetry infrastructure. It's awesome because we work with people who are passionate about racing, we truly do mean 'realtime' when we say it and we get to race and go to track days :)
Most of the incumbents are using 1990s tech and have 0 web presence. The next available realtime telemetry systems cost > $30k, and ours is $600.
We have some big plans for the future, if you're interested in racing check us out!
https://github.com/autosportlabs - Code
http://www.autosportlabs.net - Wiki
https://www.autosportlabs.com - Store
http://www.autosportlabs.org - Forums