Here's a pretty detailed and easy to use chart (not a calculator, per se, but almost as good):
Most brewing software should have a calculator in them. Beersmith (what I use) does.
EDIT: Just saw what you were really trying to figure out (not sure if that chart will help or not). Are you talking about fully carbonating at room temperature then disconnecting the gas and cooling it for storage? If so, I would think that as long as you have the correct PSI on the beer for the temperature at which you are carbing it once the liquid has taken up all the CO2 it can at that pressure and you remove the gas that's all it will hold, regardless of temperature changes.
For example: You want to carb to 2.3 volumes. Beer temp will be a constant 65F (close to room temp). You'll need about 24PSI on it. Once it reaches full carbonation (2.3 volumes) in about a week or two you disconnect the gas and toss the keg into a 40F fridge. As long as the gas is not connected your 2.3 volumes should hold steady (assuming you don't have a leaky keg). Once you put the gas back on it's a different story unless you adjust the pressure to your 40F temp to maintain 2.3 volume (10 PSI).
That's my understanding of this keg carbonation thing. I'm no physicist so I could be overlooking a major piece of the puzzle here. I'm pretty confident in what I said though since carbonation levels on beer shipped around the country from any given brewery does not experience carbonation changes. And they are usually subjected to a lot of temperature changes.
Of course, if I have no undestanding of what you really want to know and am telling you a bunch of crap you already know just ignore me.