Urban legends are also a pet peeve of mine. Whenever I am forwarded one, I always make a point of finding the relevant reference(s) debunking it and send it to the person who sent it to me, although if it was something potentially harmful (such as a virus or grossly incorrect medical advice) I would not hesitate to forward the reference to all. I am always polite about it, because I do not want people to feel embarrassed as there is never malicious intent on the part of the sender (not the original sender, obviously!).
What surprises me the most is that even fairly intelligent people fall for them without any questioning. The last one I received was from an acquaintance I consider to be well-educated, and it was suspicious from the start. It said that when you order petrol at the station, you should order in litres instead of in euros (say, order 10 litres instead of 12 euros, or the equivalent), since petrol pumps have some kind of device that can short you up to a quarter of the amount if you order in euros. This part of the hoax included a fair amount of technicalese. Well, it took me all of ten minutes in Google to find several sources indicating that there was no way this could happen, and that there is no difference whatsoever between ordering in litres or euros. I could even find a possible origin for the hoax, from a year-old post (!) at a Mexican site -and even there, it stated it was a hoax. I sent all the information to my acquaintance and his answer was that he had received it from someone he trusted so he had thought it was all right. And I believe herein lies the problem. I am sure the person who sent it to my acquaintance had also received it from a reliable source, so s/he did not bother checking it, and so on. Although checking it did not take long, it is indeed easier and faster to do a "forward to all" than a Google search, but this indicates people in general seem to prefer trusting outside sources unquestioningly than making the small effort to contrast information, and this worries me.
But I'm glad to see that we are all on the same page here! I also think that the more "gentle debunking" we do, the more people will start to see the need to find out for themselves, and hopefully, our inboxes will just be left with "cutesy" PowerPoint forwards. Which, to me, are a lesser evil but an evil no less!