http://www.velleman.be/common/product.Aspx?lan=1&id=351346
Sold as a "solder yourself"-set , for about 25 Euro at http://portal.gs-shop.de/200/cgi-bin/portal.dll?AnbieterID=7149.
has 8 digital outputs, 5 digital inputs, 2 analog inputs a,d 2 analog (PWM) outputs.
For Linux there is a piece of code from a french guy, http://linuxk8055.free.fr/. It is in a "somewhat b0rken makefile something" - condition, but it will finally build (on the page, Florian from Berlin has the right tips :). Software in the delivered state only works if both jumpers SK5 and SK6 are set, this could maybe changed. Since I only deploy one board so far it does not bother me.
http://www.controlplus.biz/k8055/ claim to have some stuff working with the board. Well, for me it did not work (10.3.9).
So I tried to build http://soft.pmad.net/k8055/. Linking with libusb installed via darwinports failed, but with libusb compiled from original source it worked fine.
A very fresh approach seems to be the stuff mentioned at http://www.hexten.net/2005/09/19/control-stuff-with-your-mac, now to be found at http://sourceforge.net/projects/k8055mac/. There is upcoming applescript support mentioned, so I stay tuned....
I have no real clue so far...