Hamachi will allow you to establish secure direct connections to PC's that are not accessible otherwise due to the restrictions in network setup.
LanTopolog is an application that provides physical network topology discovery, visualization and monitoring.
ChrisPC DNS Switch
NetSetMan is a network settings manager which can easily switch between 6 different, visually structured profiles. Pre-prescribing network settings, you no longer have to write them again when you change your network connection (for example, when you connect your home computer at work, in cafes, or frequent switching between providers).
LanHelper can scan network at high speed and it can even detect writable or read-only shared folders with the powerful and special engine. Boot (wake up) or shut down or lock your PCs.
Steam is a digital distribution, digital rights management, multiplayer and communications platform developed by Valve Corporation.
ProgDVB - the universal and very power software for watching digital TV and listening to radio channels. Support for various types of data sources: Internet TV and Radio.
J. River Media Center
J. River Media Center (formerly Media Jukebox) provides an easy, efficient way to collect, organize, and play music and other media files on your PC.
Skype is the next phenomenon from the people who brought you KaZaA. Just like KaZaA, this uses P2P (peer-to-peer) technology to connect you to other users –
Foobar2000 is an advanced audio player for the Windows platform. Some of the basic features include ReplayGain support, low memory footprint and native support for several popular audio formats.