Holidays homes
Similar to bee above - there are many properties that have been bought to rent to holiday makers ('cottages 4 you' say they have 10,000 in the UK alone) - this takes them out of the local market, pushes prices up so that local people can't afford them, and has a knock-on effect on the local economy - particularly on schools.
I'm not sure what a solution to this might be - if there is one at all, but having a lot of un-occupied properties around the country, whilst my taxes are being spent to keep people, in a variety of circumstances, in B&B's and hotels cannot be a good thing.
ttfn