Weeder Technologies looks to be a very cool company.
They make devices that connect to a standard serial port and allow for analog and digital input and output. You buy the cards depending on the function you want and they are about $60 each so the cost is a fraction of the "big" systems. They are using a very clever software hack to allow the units to daisy-chain so you can have up to 32 different modules on a single serial port.
Oh yeah -- the software to talk to all of these guys is a free download plus they are very generous with code snippets and libraries if you want to roll your own. I am looking at ultimately automating as much of the Cider and Mead production as possible and this looks like an excellent place to start.
The fact that they have been in business since 1989 indicates that they are being run well and will be around for a while longer...
I have the $119 USB based Labjack U12 from these guys:
http://www.labjack.com/labjack_u12.html
http://www.labjack.com/products.html
Source available, works with Mac/Linux and supports up to 80 boards per USB host.
A whole world of difference from buying anything from National Instruments. Pricier than what you found at Weeder, but I needed something with Mac support. Runs a control loop and a pile of 'strip charts' for a high temperature kiln.