I tried IK joints on some organic rigs (tentacles for the Cephalopod), but it didn't work out too well. I read that the IK joints in Flash work well with mechanical characters since they are sort of "mechanical" in manipulation.
Therefore, I made this AT-ST from Star Wars to demonstrate (Go figure it has reverse joints, like a horse). I worked off an blueprint image for the design. It took a little work, but here is a slightly rough walk sequence. This experiment turned out better than previous tries using the Bone Tool. My opinion agrees that it is more suited for mechanical objects.
I guess it goes without saying, but the AT-ST is not my design and is owned by Lucasfilm and/or the Galactic Empire.