Voice, Video & Text Chat Tools

Skype <http://www.skype.com>

iVisit <http://www.ivisit.com> -- offers video conferencing and collaboration solutions for PC, Mac, and Windows Mobile phones

Google Voice -- access of Google Voice account right from  iPhone, iPad and iPod Touch; free text messages to US phones and low-rate international calls; download from iTunes

YahooMessenger <http://messenger.yahoo.com> 

MSN Messenger <http://messenger.msn.com/Xp/Default.aspx>

AOL Instant Messenger http://www.aim.com/

Google Talk <http://www.google.com/talk/>