I was walking past a row of houses yesterday which, unusually, were numbered sequentially, because there was no 'other side of the street.' This made it blatantly obvious that the numbering went 11,12,14,15... there was no number 13. I gather this is fairly common now, but I'm not sure why. The house I lived in until age 11 was number 13 (Birch Road, to be precise) and a good time was had by all. As far as I'm aware it is still there and hasn't been struck by lightning.
If superstition really is so important to house buyers, I'm surprised builders get away with the gap. The composer Gustav Mahler famously didn't have a symphony labelled number 9 as he thought this was doomed to be his last symphony - so he went from the eighth to the tenth (admittedly via a piece that had the word 'symphonie' in its title)... and promptly died before he could finish it. There's a distinct suspicion that house number 14 is really number 13 when 13 is missing.
In air travel, where there's more fear, and hence more active superstition, there are examples where an effort has been made to avoid the '14 is really 13' trap. When Terminal 4 at Heathrow was built, it was constructed with gates 12 and 14 at opposite ends of the terminal. This numbering system was undertaken on purpose, so it's not obvious that there is no gate 13.
There are lots of reasons suggested for triskaidekaphobia (the fear of 13), with many ancient associations suggested - but the chances are it's a collection of historical coincidences. Clustering as was described in this post. Whatever the reason, we're stuck with it. There's lots of evidence that 13 is no different from any other number (take a look at the lottery statistics) - but human beings will always seek patterns to such an extent that they see them where they don't exist.
I'm with the bakers whose dozen of 13 was never considered unlucky, but rather as something positive. Why worry about a number, when there's plenty else in the world to get worked up about?