The best solution to the stalker problem is where anyone who isn't on your buddy list can't see that you're on. AIM does have that option. If you didn't buddy them they can't IM you.
It was so useful during OhayoCon's conception. It's so difficult to start a con when you have 20 IMs from strangers on a daily basis asking for guest contact info, free conage and even a mild amount of stalking.
"This calls for a special blend of Psycology and extreme violence"