It sounds really nice. Do you have a winmo version for sale? Also, some features (off the top of my head) that would be nice, even though I've never used it:
A PV=nRT calculator; esp. one that makes it easy to use different units, like atm or temp in celcius (l-atm/k-mol vs. j/k-mol)
A humidity calculator (i.e. saturated conc of water vapor in air as a function of temperature, or the conc of water vapor at a given humidity and temp); or, maybe just an Antoine equation calculator, with a database of constants for different liquids, as well as the possibility to import constants for things that aren't stock.
Unit converter (like temp (C, F, K) and pressure (bar, atm, psi...))
Anyway, wish I could use it, and good luck!