Some time ago Hobbyking introduced their i86 control board (US$ 21.99), based on a Atmel Mega168PA 8-Bit RISC based micro controller and a single 3-axis MEMS gyro. No mounting holes, you just have to tape it to your frame with double sided tape.
The nice thing about this controller (apart from the powerfull micro controller) is that it comes preconfigured for Tri copters, quad copter (X/+), hex copter/H6 copter and Y6 Copter. You can select your type of frame by setting the dip switches in the correct settings. All of the mentioned modes can be set in "Normal" mode or "Sports" mode (default normal). There is no need (or possibility) to upgrade firmware. See image below for the setting your frame.
Today Hobbyking released a new version of this multi rotor controller, the i86L (Light Edition) (US$ 18.99). Apart from pricing it is not yet clear what the exact difference is or are between the orignal i86 and the i86L light version.
Specifications for both controllers are:
Input Voltage: 4v to 6v
Input signal: 50hz standard PPM
PWM Frequency: 400hz for , 50hz for servos
Gyro scale: +/- 500dps, ODR: 800hz
Operating temp: -40° C to 85° C
Size: 40mm x 40mm