chobit

I put UV filter on all my lenses.  Used to be Hoya HMC or better, and now using B+W MRC (forgot the name).
I totally agree with Happy_Cow about the potential sharpness/IQ loss is nearly 0.

By the time you have are ready to clean the dust, sand or salt on your lens, you will feel so much better cleaning it off your UV filter then the front element of you lens.

That's says, I don't recommend using cheap non-coated glass filter.