Apache MINA
http://www.ibm.com/developerworks/cn/opensource/os-cn-apmina/?S_TACT=105AGX52&S_CMP=techcsdn
Grizzly
http://www.javaeye.com/news/4489-grizzly-1-9-released-new-twitter-demo
Quick Server
http://www.blogjava.net/calvin/archive/2006/08/12/63260.html