LAN Messenger - LAN Messenger is a decentralized UDP IM-style chat client which supports usernames...
Dingtone - Dingtone is a free call and texting application for making unlimited calls and text messages to any number at the moment registered in any part of the world by any cellular company.
Softros LAN messenger - LAN messenger for an internal office chat for home or business users. It does not require a server and is very easy to install and use. It supports personal chats, group chats, message brodcasting, files transfer and remote desktop access.
Textnow.com - It lets you text your friends, aka my only source of happiness
MyChat - Secure instant messenger for any network
FluffyChat - Open. Nonprofit. Cute ?