If you’re looking for a networked device monitoring system and you’re a Windows admin, then IT Desktop might be your dream come true.
A free download, ad supported, this basically supports pretty much every type of inventory you can think of from software, hardware, to licenses and asset tags. It even tracks your network and Exchange traffic for you along with giving you fun little displays and sets up a IT Help desk/portal for all things internal. Suitable for pretty much anything you need to do in a small corporation.
All that with only a 7MB footprint. Not bad! It does require you to run XP Pro SP2, Vista, or Server 2003 and the clients must be Firefox or IE. Outside of that, the world is your oyster! Well, maybe just your corporate network.