If you have Sony PSP and want to chat in Yahoo Messenger or AOL Instant Messenger aka AIM or Windows Live Messenger aka WLM or MSN Messenger, you can do that by installing PSP Messenger on your Sony PSP (Sony PlayStation Portable).
PSP-Messenger allows you to access Yahoo, Aol and MSN messenger services on your Sony PSP for free. Keep updated on the official Website of PSP-Messenger. This is easy to use and works well on PSP. It also works on PC if you want to test it first.