LOL! I'm afraid I have too many projects in the works to start a compilation of all the actions and their effects, but thanks to the person who pm'd me.
I will add that the treadmill is awesome for energy levels. What it does is cause your peep's energy (and hunger) levels to drop more slowly (in effect, gives them better endurance.) I've had a peep who was hungry become not hungry just by walking on the treadmill (while waiting on their meal to be prepared.) Additionally, if your lil peep is exhausted, dropping them on the treadmill will either force them to take a nap (they'll shake their head and tell you "No" but their action will be "Taking a Nap" and they will go to the living room and do so;) or they will actually walk on the treadmill and recover a small amount of energy by doing so (I've had a few change status to "Tired".)
Good luck to you.