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Try it out: http://saintamh.org/apps/flats/
Source (plain): svn://svn.saintamh.org/code/flats/trunk/
Source (highlighted): http://svn.saintamh.org/code/flats/trunk/

I first created this program when shopping around for a flat in Nancy, then later "ported" it over to Edinburgh. Once a day, the program goes and scrapes the websites of a bunch of real estate agencies, and extracts from them their current offers. It then displays a map of the city on which the flats are shown, and some basic filters for narrowing dows your search.