TwitterMatrixTweeter, consisting of a BeagleBone and a dot matrix printer watching for tweets mentioning my Twitter username. It got picked up by several large blogs, and made for a rather entertaining week as tweets spewed out of my printer.
Special thanks go out to the commenters Joshua for managing to find the NP-10 user guide (part 1, part 2), and 0x6D64 for porting the code to OSX. Finding the user's guide was particularly useful since it gave me the "ESC - i - 1" command sequence to put the printer in "immediate" mode, where it would automatically move the paper up out of the ribbon between tweets to make it easier to read. It also gives me all the information I need to put the printer in bitmap graphics mode, so the printing possibilities are now essentially endless once I write the drivers for it. Thanks again to Joshua for the find.
In any case, lots of newspaper, my MechE tendencies to get absolutely filthy, and ten minutes of very carefully repacking the ribbon into the NP-10 cartridge was fairly successful. The FX80 ribbon unfortunately doesn't have the half-twist in it, so the printer will only ever use the bottom half of the ribbon, and I would eventually need to pull the cartridge and vertically flip the ribbon if I wanted to use the top half.