Today's inspiration for you is Blender's iTaSC IK Solver. I haven't found any tutorial on Blender's main tutorial sites, but there are some interesting demo videos out there:
Official Blender description:
Algorithm description: http://wiki.blender.org/index.php/Dev:Source/GameEngine/RobotIKSolver/Algorithm
iTaSC tracking 2 targets on the same bone from ben2610 on Vimeo.
Blender iTaSC IK solver realtime action in the GameEngine from ben2610 on Vimeo.