Talking to friends online

There are a number of ways people can communicate online in realtime. IRC and instant messaging clients are two highly popular mediums for this type of communication. Among these, the the most popular are AOL Instant Messaging system (AIM), Yahoo! Instant Messenger (YIM), ICQ (A cheesy word-play on "I seek you"), Jabber, and Microsoft even has one too (MSN).

Instant Messaging Clients

• pidgin is a Linux application for AIM, IRC, ICQ, Jabber, MSN, Napster, Oscar, TOC, Yahoo, and Zephyr.
• AOL has an official client, but it is quite ugly looking and not nearly as capable as pidgin.
• Jabber
• The Chandler project actually aims to use it for transmitting information between computers.
• aMSN is perhaps the best MSN client for Linux. It has almost all the features of the Windows version, and some it doesn't possess. It's rather lightweight and uses the tcl/tk packages.
• Kopete
• Bitlbee
• Centericq...

IP-telephony

• Skype

Voice chat

• teamSpeak

IRC

• Kopete
• irssi
• Xchat