Some people I know have been involved with this:
This will be primarily of interest to prospecive U.K. voters: it's essentially a means of identifying the party whose views are closest to your own. It works this out based on comparing your answers to a 23-question quiz with the party manifestoes of the big three parties, plus the Greens and U.K.I.P.
I come out as heavily Lib. Dem., with the Greens trailing in second place and the Tories a very clear last.
It's obviously rather reductionist, but it covers the main areas of contrast between the parties with admirable clarity. Plus they link to a site with some hilarious animations taking the piss out of Robert Kilroy-Silk, which is never a bad thing.