Now that we are definitely gong ahead with a property web app I have done some research to give me some ideas.
The site I liked best was Right Move, This site has a simple home page with the main feature being the search box at the top of the page. This appears to be so users can quickly search for property to buy or rent without getting bogged down by other information. If users want to sign in or register there is just a small link at the top, which is obvious if you look for it but doesn’t distract from the main feature being the search.
Another site I looked at was Zoopla, this site has a very different feel to Right Move but maintains the concept of having the search the dominant feature. This appears to be a trend in sites that offer services, I would suggest that it is because the purpose of the site is to help people find a property and advertisers would want this to be the main feature. I also noted that this site also has a deliberately clean feel to it, in that the home page is not cluttered and everything is easy to find.
Although these are not the only sites I looked at they seem to optimise what I would want in such a site.