Armagetron Advanced 0.2.8+ has a feature to record a play session. This session can later be used by developers to find and squash bugs.
armagetronad --record ~/place/to/save/your/file
armagetronad [--fast-forward TIME] --playback ~/file/to/open
Mac OS X
Use the helper application to start/playback an Armagetron Advanced recording. The application has a feature to compress a recording using bzip2 after Armagetron Advanced quits, so you can upload to the forums easily. If you open a bzip2/zip file for playback, it will be decompressed and played.