I grew up around Key Limes... (when we lived in the Florida Keys my aunt had one in her yard) and I really love them, especially in Key Lime Pie! They are also delicious in beverages, sorbets, and jams. They make excellent marinades for fish (like seviche) or meats, chicken and salad dressings.
Most of the Key Limes available now in the grocery stores are grown in Mexico, but it's still a Key Lime. Unlike regular limes (Persian Limes, a hybrid), Key Limes are yellow when fully ripe, so if you buy green ones, let them ripen on the counter or in a paper sack for a wee bit. Watch them carefully; the skin is thin and they dry out quickly.
On an infrequent trip to WallyWorld 50 miles away, I bought 2 bags of Key Limes on a whim. They were on sale for 88¢ for a 1 pound bag, almost 2 dozen limes per bag. (My local small town grocery store would never carry Key Limes!) However, I'm not ready to do anything with them and don't even have time to juice the little rascals since a friend just gave me a deer. To experiment, I froze one whole lime for 48 hours to see how it would hold up.
Frankly, I am surprised and quite pleased at how well they did. The cut lime in the photo above was defrosted at room temperature for about 30 minutes before I cut it. It is juicy, and not mushy at all, although the skin might not be good to zest just because it's thin anyway. (The others in the photo have not been frozen yet, just shown for color.)
Given the price of lemons and regular limes in the stores, I wonder if they could be frozen equally as well? Most of the lemons I find anymore are hard as rocks and don't have much juice at all, but occasionally there are a few decent ones, albeit expensive. If they froze well, I could put a few in the freezer when I find good ones. I need to try it!