Today while i was on Construct i went about trying to build a simple IK bone system and came up with this.
Its not perfect yet, as i havnt found the correct # relationship for something (its illuding me but i'll find it soon!)
The reason its not perfect is the target point of the IK does not represent the excact position where the end of the chain will land (it deviates about -10/+10 pixels) but is still very usefull. The other end stays excact so... if you would like an excact end point and a deviating shoulder just switch em around!
This is very easy to use and can be very useful for character animation