Pecon used applications on his Boss Battles server because he wanted a large administration staff, and "My friend isn't an idiot, no really I swear" only works so far down the chain. We review with really strict standards, for every one that gets accepted we reject like fifteen applications that have something like "I will not abuse, I just want to help the server" in them. (And if you can't tell what's wrong with that then you definitely shouldn't be running this kind of system.)
The results of the system are pretty good - we have like 40 administrators and have only ever needed to remove a few for abuse. Most of the ones that get removed are for inactivity, so the ratio of accepted to abusive is pretty good.