LastPod is a tool that will parse the "iTunesDB/Play Counts" file from an iPod and submit played tracks to AudioScrobbler (http://last.fm). LastPod directly interfaces with Last.fm, no additional software is required. This method is fairly unique, and I have only found a few other applications that support this usage model.
If you have not done so already please download and try LastPod. I believe you will really enjoy using it.
The project is released under the GNU Public License (GPL). Please feel free to review the code and/or suggest improvements.