networkpacketanalysistool.jpg Packetyzer by NetworkChemistry for Windows that’s free. It uses the Ethereal engine, but puts on top of it a more usable GUI, and allows you to configure it and filter the packets and capture it for whatever you’re looking for.
What’s interesting is that I don’t seem to see anything that’s that much different from Ethereal’s Windows version except for the RFprotect Mobile integration. According to this, it can sniff 802.11 packets and watch control and management frames.