If you want to video chat with friends who don't use an iPhone, Facetime is limited. These alternative apps can video chat, text and make calls for free.
1group chat
iPhone and iPad apps tagged "group chat."
BeeJive, When IM Matters More than Anything Else
There's been a lot of buzz about Beejive's BeeJiveIM lately. That's easy to understand because BeeJiveIM with Push is a very capable IM app. It puts everything IM-ish under one roof, which other IM apps don't do quite as well.
