rusEfi - electronic fuel injection / engine control unit for a car. Open source, based on stm32 - using stm32f4discovery for now.
A little bit of background: I am a software developer by trade (core java, high performance java - financial industry) and cars are a hobby. At some point I've got interested in turbo-charting the car and this lead to looking into the configurable ECUs - "engine brains" - and I've realized that the most of the products on the marked are closed-sources, and the open or relatively open ones... I've realized they are a bit outdated - no FPU, hardware hacks, poor code readability etc...
So, I've checked the state of embedded programminig and I've realized that things are not as hardcore as they used to be - you can now program chips via USB, you can get a 168Mhz dev board for $15 - a LOT of CHEAP power, and noone is using it so far!
Here comes rusEfi - http://rusefi.com/
Source code lives at https://svn.code.sf....trunk/firmware/
Here is an article from developer point of view - http://rusefi.com/articles/tachometer/
So if anyone would be interested to contribute & play with all this, if you know software and curious to contribyte to a real-life project - please do not hesitate