Real estate listings. Only limited information on a MLS is viewable without a broker. And getting your house information on one can cost 200 to 500, or up to 6% of the price. There are already free internet listings, but those can lack listings and information on houses.
Seconded on all things real estate. This is more of a legal/social problem than a technical one at this point. Websites like zillow.com make a real estate agents role largely obsolete, yet they still try to command a huge commission on every sale. Another poster above mentioned Title Insurance as well.
I suspect over the next 5-10 years we will see major changes in this industry. Huge savings to home buyers & sellers are available if the bureaucracy and traditions can be broken and replaced with a more consumer friendly system.
Zillow hardly makes the role of a real estate agent obsolete - first off, their Zestimates are no where near correct in a lot of markets especially Today with all of the foreclosures and short sales. Second, the process of purchasing or selling your home isn't any easier because of zillow - only marketing a home is easier.
A consumer friendly solution is needed - when we purchased our home last year, the amount of times I needed to initial and sign documents and then sign again after changes and again when the conditions were met, and again when we removed the contingencies, etc - and each time Scan & Email or Fax it back to the sellers or a third party; it was just annoying. With all of the e-sign technologies and document collaboration, there has got to be a way to make this process easier, smoother and less archaic.
We got our home for a great price, and used a real estate agent, I could care less whether or not the realtor was removed from the process. What I want removed from the process is the pain.
There's already many competitors and real estate isn't exactly an awesome market segment to be in right now. Zillow, Redfin is actually doing something different (replacing one of the agents and returning savings to customer).