APM Control board For Multi-rotors UAV

Ardupilot Mega 2.x for Multi-rotors UAV from DIY Drones

The ArduPilot Mega 2.x is a complete open source autopilot system, it allows the user to turn any MultiRotor capable of performing programmed GPS missions with waypoints.  The OS / Firmware for the APM 2.x for MultiRotor’s is Arducopter.

apm2.5 from Diy Drones

apm2.6 from 3DRobotics

Features
Arduino Compatible
  3-axis gyro, accelerometer and magnetometer, along with a high-performance barometer
  Onboard 4 MP Dataflash chip for automatic datalogging
  Digital compass powered by Honeywell's HMC5883L-TR chip, now included on the main board
  Optional off-board GPS
  Invensense's 6 DoF Accelerometer/Gyro MPU-6000
  Barometric pressure sensor, MS5611-01BA03, from Measurement Specialties
  Atmel's ATMEGA2560 and ATMEGA32U-2 chips for processing and USB functions

APM Planner can be downloaded from here:  http://code.google.com/p/ardupilot-mega/downloads/list
 
Mission Planner is used to upload new firmware, for calibrating your APM 2.5 and checking and calibrating your radio

The Planner can also be used for following
  Updating firmware
  Calibrating radio
  Calibrating horizontal and magnetic settings
  Setting up Attopilot Voltage and Current monitor
  Setting up Ultrasonic sensor
  Tuning PIDs
  Setting flight modes
  Mission Planning
  Ground Station