My guess is that there are none. First of all, windows is pretty resource intensive using 1 gig of ram atleast on startup, it might be possible to run windows RT on a raspi like board but I think it would be prettys slow. Then there is the cost, linux is free, windows costs a lot of money (about 3 times the cost of a raspberry pi). I also believe that windows is not as good as linux when it comes to handeling "physical" output like the pi which would make it pretty useles...
Out of curiosity, what are you planning to do with it?
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