The Nintendo DS, when used in conjunction with some extra hardware, can playback a form of MPEG-1 file designated as .DPG format. There's a whole thread devoted to converting DVD's and .AVI files to this format here:
DVD/MPG to DPG Guide (for Nintendo DS) - VideoHelp.com
The only problem is that it doesn't discuss how to pull off this task using Mac-only software.
Is there some way to pull this off with FFMPEGX or any other applications on the Mac?
I would've thought that this format would be added to the list of alternative formats in FFMPEG, but it still doesn't in the latest release (of course they do have "for iPod" and "for PSP" choices already available).