1)   MAPILab Groupware Server 1.5.3.2
MAPILab Groupware Server is a cost effective alternative to the traditional methods of Outlook sharing. It allows you to easily share contact details, message folders and more over your network without requiring Microsoft Exchange Server.

 2)   OLfolders PE 2.8
Share Microsoft Outlook in a network without installing a complex server application. OLfolders PE allows sharing personal data files with 5 users in a network. It runs under any version of Windows from 95 to Vista and Outlook from 97 to 2007

 3)   ShareO for Outlook 3.51
Share Outlook folders without server. Microsoft Outlook add-in for synchronizing and sharing Outlook folders, sharing PST, sharing email, sharing calendar without Exchange. Share calendar, share Outlook contacts, sync Outlook contacts, address book.