The Asus WL-700gE is an interesting device. It provides NAS, streaming and routing services thanks to linux. In their quest to modify the WL-700gE to a more flexible platform, [Eric] documented adding a serial port to its not so spacious innards. (FYI, Standard serial/RS-232 signals are around 5 volts ok, more like 12. I was thinking of the max 232/n variety) Asus was kind enough to provide through hole mounts and a TTL interface right on the board with console access already turned on.
I hadn’t realized it before, but the Siemens phone USB data cable is a nice cheap source of USB to TTL serial interfaces. Ironically, replacing the cable on the data unit was actually more difficult than adding the port to the router.