Read the latest issue of Nuts and Volts and this one highlights an Analog Shield for the Arduino, but with truly interesting specs: 4 channel A/D, 16-bit, 100 ks/sec, and 4 channel D/A, 16-bit, 100 ks/s. Digilent is making them- the board was jointly developed by Stanford and TI. Schematics on Digilent show a pretty straight forward design. Uses the TI converters: ADS8343 and DAC8564.
I have not yet acquired one, as the magazine just arrived today, but it appears that this shield is controlled via SPI. Advice in the article points the interested reader to github.com/wespo/analogShield to obtain drivers with a bit more operational stability than those Digilent evidently supplies.
Point is, we now have a reasonable analog board to play with, that can be used for truly interesting and useful things (100 KHz sample rates and 16 bit resolution will find immediate use in many higher end applications), but the driver software will require a port for the prop.