This action will take an Origin position and compute an intercept point for a moving target based on a speed variable. It's not perfect, but can be pretty powerful as is.
I'm working on AI and compiled this in an hour or so based on some reference code found on the unity forums (creds in code). Please feel free to test it and make suggestions or adjust it yourself.
// 21-Aug-14
// LeadTarget minor update to be in Physics category and check for Rigidbody on The Target.
// LeadTarget2d added