Luminous-Landscape.com has an answer to that age old debate: Should you use a UV filter or not?
Several good points are made — the practice of using a UV filter is an age-old one and was valid by all measures a while ago. Today, however, it seems the lenses are made to withstand a lot more.
I have had a time when a UV filter most likely saved my lens. Shortly after purchasing my D60 (a few years ago), I took it out on a test-shoot. The light outdoors was dimishing, so a default focus assist beam (which I have since turned off, as it is almost entirely useless) flashed while I was focusing. An insatiable firefly mistook my D60 for another of its kind and tried to mate with my camera. “Thunk!” The bug would’ve smashed into my lens, but the sturdy UV filter blocked it from doing so.
Now the odds of something that peculiar occuring are pretty slim. For oddball cases, I imagine that’s why there is camera insurance. Most anything that could break the lens with a UV filter on could also break a lens not wearing a UV filter.
I think I’m going to try not wearing a UV filter on the front of my camera’s lenses for a while — and possibly will pick up some of those nifty MRC filters mentioned in the article for weather conditions.