Acute Softwares Network Diary - Single User Description:

Allows small businesses and companies to share appointments from a central server. Each user on the LAN runs the diary Client, which keeps their own appointments, file usage and PC usage on their own PC. To make appointments public they simply tick a box and it is automatically copied to the server.

This is a single user License only - it does NOT include the full functionality of the server, but it can be run in stand-alone mode, with all the tools like the Timesheet generator, date calculator, InfoLink toolbar and reminders.
Use this form to purchase additional licenses if you are upgrading from the 5 user pack.