InOut Tracker for Mac

From Startly Technologies:

InOut Tracker is a people tracking tool that works across your TCP/IP network. With an easy to use interface and simple set up, your employees can locate one another in a hurry. Gain instant access to the in/out status of employees or co-workers. Find out when they will be returning, or the best way to contact. InOut Tracker will even launch your favorite POP3 e-mail client if that is the preferred method of contact. Get InOut Tracker to stop searching and keep working.