1)   OfficePopup 2.30
OfficePopup allows the management team to inform employees about any important events or incidents by sending messages to entire departments or individual users on your network. OfficePopup runs on any TCP/IP based local area network (LAN).
winpopup, messenger, popup, lan chat, intranet instant messaging, winpopup for windows NT, home network, real-time messaging, intranet messaging, messaging software,

 2)   DynaTalk 2.0
DynaTalk is an easy-to-use application that allows you to send and receive text messages on a local network. DynaTalk doesn't require special configuration or dedicated servers.
instant messaging, local messenger, messaging, talk, message, messenger, chatting, lan chat, intranet instant messaging, winpopup,