About 18 months ago, I got some small and modest-cost boards. They have 8 digital inputs, 8 digital outputs, 4 analog inputs (one is set up for 0-3.3V, the others are 0-10V) and 8 temperature (DS18B20) inputs.
The new version of this board will also accept a second ADC for another 4 channels, I believe.
DOESN'T have USB, but to me that's a good thing. I hate USB. It does have Ethernet though. You can query it over the net (linux, windows, whatever you want) and set outputs. It can operate stand-alone. It has about 4,000 lines of PLC code memory so you can load a whole bunch of smarts into it and leave it do its thing (if voltage gets below X for Y time, and temperature 1 is below z degrees then turn on output n, and send an email) - all while being able to monitor it remotely.
Here's one I've mounted up in an IP67 box, along with 4 output relays and a 3G cell-router to talk to it.
Cost varies depending on who you get them from, but $50-$70 is about right.
For measuring a shunt, you'd need an amplifier, Tom. Or... use one of the hall devices. The ADC is only 10-bit which is a bummer, but most inexpensive stuff seems to be.