AOL IM Palm the older version is free, it does all the things I need.
I don’t often use the IM on the phone. SMS is more practical. But sometimes you need AIM to contact people. I keep it on the phone. I’ve used it maybe a dozen times in 4 or so years. But it is one of those things that when you need it, you need it. So better to have it set up and ready to go on the phone even if you don’t think you’ll need it.