When it comes to wireless Apple Wireless Keyboards, you need a bit of a specific kind of protector as the keys are a bit short. These covers aren’t hard to find, but it is very difficult to find thin, clear covers. You will however, find thick, pink, blue, and green silicone protectors that won’t let you see the keys properly.
Recently I stumbled upon the Moshi ClearGuard keyboard protector, and it looks to be quite promising. It boasts being one-fifth the thickness of other silicone protectors, but will still give you the squishy comfort of something between your fingers and the hard plastic keys. It does cost $25, but considering the money and time it will save you if you happen to spill your coffee all over your keyboard, this is a steal.