There are a bunch of websites that give you houseprice information - it's just the Land Registry data, with a nice front end, really. So you don't know if the place is gold-plated or a burned-out shell.
At the weekend, a conversation led to this idea - there should be comments on these sites. My preferred site is Houseprices.co.uk but they're all much of a muchness. What you really want is local colour, "did you see what the Levines did to their kitchen? Abortion." "I mean, they ripped out all the fitted furniture and carpets, and did wooden floors and fireplaces, can you believe?"
Comments, that's what would differentiate one set of houseprice data from another. A libel lawyer I'm not (although I don't know if you can libel a house, I suspect not), but it would be interesting, no?