There's going to be as much debate about filters as there is over film vs digital. Short answer is, everything has its place.
I got a cheap Tiffen UV for my general-zoom when I got my first (d)SLR. After a few months and a few tests, I got rid of it. I could actually see the difference that it made to lower IQ (not only the vignetting at the wide end).
But then a few years later, I got the new Canon EF 70-300L, and put on a B+W MRC filter. Testing and pixel peeping with and without, there is absolutely no difference to IQ. Not only is it better glass, but it's multicoated (unlike the cheaper ones), and it's easier to clean with some fancy coating.
Sure, lens hoods protect against falls, but lens hoods also tend to prohibit using CPLs (in general, but I hear Pentax makes a nice one with a cutout). And lens hoods just won't protect against sandblasting. Maybe you don't go down to the beach and shoot surfers, but I do. It's dusty and windy and sandy here in Aus.
So if I'm going to shoot surfers or birds on the beach, it's UV and no hood (sometimes with CPL, I've also got a nice KSM CPL for that lens). If i'm shooting indoors on stage (with lots of incidental light from the roof), it's hood and no filter (well, sometimes filter, like I said there's no IQ loss so sometimes I just leave it on. And yes, I know a 70-300L is hardly a fast indoor lens, but if i'm using Delta 3200 there's no harm in going an extra stop to 6400).
Also, see this: http://www.lenstip.com/113.1-article...ters_test.html
tl;dr: B+W MRC are good. Tiffen are junk. Good Hoyas are good, bad Hoyas aren't. Marumi ain't bad.