I like this idea also. Here are 2 links to parts I use for data logging and data acquisition on my Arduino weather station.
This little guy connects to Arduino's TX line and just logs anything sent.
The next part is a MAX6818 octal debounce chip with interrupt output. I use it for switch inputs and to count pulses from the mechanical rain gauge.
http://pdfserv.maxim-ic.com/en/ds/MAX6816-MAX6818.pdf
Just a couple suggestions.