From time to time, I'll post a quick mention of things that I find are quite cool uses of technology.
Many Epson printers indicate an empty ink cartridge by slewing the print head assembly so that the empty cartridge lines up with a pointer molded into the printer's top case. There's little a simple printer — one with no display — can do to communicate which cartridge needs replacement. Moving the head to signal is very elegant.
Griffin Technology SmartDeck cassette adapter for iPod. This ingenious device senses the normal tape motions (rewind, fastforward, play, pause, and stop) and creates the appropriate commands for an iPod.
Most modern all-in-one printer/scanners are able to scan in their own alignment printout sheets! Older inkjet printers used to print alignment sheets, usually with numbered samples; the user then entered the best sample numbers to the software so that the driver printed with the best alignment. Some HP printers even have the ability to scan the alignment information while printing it, eliminating the need to for the user to scan the printed sheet.