He was at the wrong place at the wrong time.
To be honest looking at it from zimmerman's side, Travyon may not have appeared to be doing nothing.
As stated before the neighborhood had many recent break-ins mostly commited by "black" people.
If trayvon was cutting through houses and just looking around, yeah it could have looked kinda suspicious.
Also only reason that zimmerman got of was because the prosecution couldn't prove that zimmerman didnt shoot trayvon in self-defense and many of the prosecutions witnesses testified to the fact that Travyon and zimmerman were engaged in a fight and that one was on top of the other.
Yes this was a Legal homocide and is protected by law. It doesnt make it morally right though.
But you cant judge people based by morals because thats just plan unfair and is not justice.