VSL LanToucher Network Messenger 

LanToucher is a full-featured, Microsoft WinPopup-compatible LAN messenger for Microsoft Windows 95/98/NT4/2000/ME/XP/Server 2003. Designed as a WinPopup and "net send" replacement, LanToucher provides many more functions, options and features.
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CoolPopup 

Easy-to-use WinPopup replacement. Are you dealing with the problem "how to make everybody get to work without talking to everyone individually"? Use CoolPopup!
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