GeckoReader is a program to be run under Windows that will open a command prompt and output what it reads from a USB gecko. You must have the USB gecko installed, set up the COM drivers, and have .NET 2.0 for this to work properly. Then whatever buffer is sent from the Wii/Gamecube should pop up on the screen.

Changes:

Can send a file or data stream to Geckoreader, which will save the buffer as a file
Can make a hexdump of a buffer, which is sent through the gecko

http://wiibrew.org/wiki/Geckoreader