Question: This question may be interpreted as "too localized", but it is not.

I'm interested in what you find to be the best sites for this type of operation, regardless of where they are located. For instance, I want to learn about how do these sites do the following:

* How do they work with geographic information?
* What search parameters do they use?
* Can you personalize your search? How?

and so on...

Answer: 
The ones I've had most sucess with is:

* [Rightmove](http://www.rightmove.co.uk/)
When I was looking for my house, I found [Trulia](http://www.trulia.com/) to be very helpful in terms of the search and notification options it has.

Geographic Info: Search by city and zip code. You can also have it show everything within the visible Google Maps area. For cities and such, you can also select specific neighborhoods.

Search Parameters: City/State/Zip/Neighborhood, Price Range, # Bedrooms, # Bathroom, Open Houses, New Listings, Listing Type, Property Type, Square Feet Range, Keyword, Year Built, Lot Size, Foreclosure Type, MLS ID, Price/sqft.

Personalize: Yes. You can save searches and receive email alerts.