ICQ

the author of this app says:

ICQ is a revolutionary, user-friendly Internet tool that informs you who's on-line at any time and enables you to contact them at will. No longer will you search in vain for friends or associates on the Net. ICQ does the searching for you, alerting you in real time when they log on. The need to conduct a directory search each time you want to communicate with a specific person is eliminated.

Requirements

2.0 Only