NetResident

From TamoSoft:

NetResident is an advanced network content monitoring program that captures, stores, analyzes, and reconstructs network events such as e-mail messages, Web pages, downloaded files and instant messages. While NetResident is similar to network analyzers in many respects, it focuses on high-level protocols that are used to transfer content over the Internet or LAN. With NetResident, you don't need a profound understanding of networking technologies, have to use complex packet capturing and analysis software, or dig through network packets in order to reconstruct the actual data; NetResident does all the work for you and presents only the Web pages, e-mails, instant messages, or downloaded files as requested. NetResident is used by network administrators to enforce IT policy, parents to monitor their children's communication on the Internet, and by forensic experts to gain crucial information.

Version 1.2 build 231 adds support for VoIP protocols.