I'm impressed. Last time in February, the site consisted of just a few mockups, and lots of ideas about how to revolutionize real estate search. Nine months later, they've already built the site, signed up lots of partners, built very sophisticated back-end analysis systems, and got press attention. Good job!
Unlike other websites whose interest it is to keep you on their site so they can show you banner ads, Nestoria works on a referral basis. It's best for them if find what you're looking for as quickly as possible. They're doing a great job at keeping the site very simple. However, their results pages provide a huge amount of useful information: Maps, closeby tube stations, hospitals, and schools, congestion charge indicators – they even have different pins for each of the tram systems in the UK. The latter requires quite some effort: Apparently, British real estate agents typically write longish descriptions of each property: Cutting that down to a reasonably short summary on the results page requires some non-trivial processing.
Their site is so good that Google technology evangelists are using it to pitch the Google Maps API at real estate conferences in the UK.
I wish there were a Nestoria Switzerland: I'll need to move out of my fancy university-subsidized room very soon. Update: As one of the commenters pointed out, immo.search.ch is actually pretty good, and that's what I'll be using.