Yuo could use something like
this. $50 Canadian.
It's a serial (RS232) data logger, that has FAT16/FAT32 capability. Essentially, you could generate a standard readable text file on the unit, take out the SD card and read it in a PC/Mac.
Gumstix is another idea (which someone mentioned earlier), but it will be more costly and probably more difficult to implement. I've got one (with a few of the modules :-))... and it's fun to play around with - but will probably be frustrating to those not familiar with linux.
Good luck!
- Jeff