Netresec released a new Windows network sniffer tool that looks promising: RawCap. It has no winpcap dependencies and with its small 17kB foot print it does not require installing. (Having said that you still need .NET Framework libraries and DLLs.)

Here are the properties of RawCap from their webpage:

• Can sniff any interface that has got an IP address, including 127.0.0.1 (localhost/loopback)
• RawCap.exe is just 17 kB
• No external libraries or DLL’s needed other than .NET Framework 2.0
• No installation required, just download RawCap.exe and sniff
• Can sniff most interface types, including WiFi and PPP interfaces
• Minimal memory and CPU load
• Reliable and simple to use

For downloading and some screenshots and more information click here.