I've used Ethereal for some years now. This software was updated the other day, if you have an older copy you might want to update for new features. If you use Ethereal, you know that it is an Open Source network protocol analizer that runs under Linux, Unix and Windows.
Developers and security professionals may use a protocol analizer to capture packets on the the network and look inside the traffic to troubleshoot netowrk problems or even to look for signs of intrusions. Network Chemistry has a similar product that uses parts of Ethereal, and prvides additional functionality. Their "Packetizer" software, which makes use of the Open Source philosphy of cooperation is licensed under the GNU license, and the source code is freely available. Packetizer is a protocol anaylizer that is specifically designed to look at wireless LAN packets. The Packetizer is part of a larger suite of security products that Network Chemistry offers.
I thought the site and the product merit mention as an example of how a commercial organization can contribute to and benefit from the Open Source community.
If you're running wireless, for heavens sake, please run some kind of IDS too. If you don't know about these 2 tools you should look into them and also do penetration testing on the wireless segments of your LAN.