Simply put, there is none. Once ground, coffee has about 15 minutes of life before enough of the flavor components are oxidized that it is merely a ghost of its former self. Whole beans stay reasonably fresh for about 15 days after roasting, so, as stated above, the best option is to buy fresh roast, grind as needed, and use within two weeks.
Agreed that it's best to store as whole bean (rather than ground) and use the beans within 15 days or so. But there are times when the coffee is ground (for whatever reason), and you are just not going to be able to use it right away. I know this is hotly debated, but IMHO you can stall off the stale taste if you package the coffee in a good airtight container and put in the freezer. There, I've said it...bring on the naysayers!