Hey,
Glad you like the idea! I was thinking 0-5V, 4-20mA (using a shunt), would be nice to have 30k thermistors (pretty cheap and lots of them), digital pulse counting and maybe also 1-wire?!?! Of course, the 10bit A/D might be a small stumbling block, but to be honest, most applications really don't really require anything with a higher resolution. Also, have the ability to trigger a digital channel on an alarm condition.
As for software on the PC side, I was thinking a simple/basic programming interface, for example, the user could enter the sensor type (i.e. 0.5 to 4.5V), the scaling and logging rate. Then can download the data and export it as a CSV format, all straight forward stuff. I guess my main thing would be packaging, making it as simple as possible for the non-technical user.
What do you all think?