Well... a polarized filter is good for anything that gives off a reflection (not just water). Any glass, windows, snow... anything really. The polarizer also tends to saturate skys and really tends to add to the photo (in my opinion).
A UV filter just blocks out UV light and reduces haziness (and provides protection for your lens). There are a lot of arguments around the use of a $50 UV filter on the front of a $1000 lens and the fact that the filter degrades image quality. I personally use a UV filter when I'm shooting any sports to put an extra barrier between my lens and whatever could hit my lens. However in the studio or when I'm doing portraits and product work and there is less chance for something to break my lens I take the UV filter off.
This might explain things a little better: http://en.wikipedia.org/wiki/Photographic_filter