I've used Mina and Netty, but now I'm in the market for a lightweight library that may also be used in Android. I prefer Nio or AsyncIo over standard io implementations.
Update 1
The lack of responses really makes me think I should write my own library. Right now I'm using raw NIO and its not a lot of fun.
Since this seems to be dead on arrival, I'll answer it by saying my custom IO library will be the best.