I could certainly use the digital inputs, but it would be a waste at only 16 available bits (I'd need to multiplex, and for that I'd need to either synchronize to the packet stream or go real slow, which would be a pain)
The digital pots do look like a good solution, and they're not too expensive either. Specifically, these (from Microchip, hah) look like a pretty good choice at $2.65 each (we'll probably use three or four of them to give 6 or 8 inputs).
http://www.digikey.com/scripts/DkSea...604125&Site=US
http://ww1.microchip.com/downloads/e...Doc/11195c.pdf
Thanks for the answer! I'd completely forgotten about digital potentiometers.
Out of curiosity still though, does anyone know what the input section of the OI looks like?