It would look good if you self-studied and got a good score (like a 4 or a 5)...
but if it may hurt your other activities, I wouldn't recommend it.
I'm taking AP Psych right now in school, and I would say that it is quite self-studiable (if such a word exists D
.
I think the fact that you are taking 5 AP classes shows colleges that you're a hard worker and a motivated self-challenger.
Best of luck~!