The advantage of real estate websites is that they can provide a useful overview of the housing market in any particular area with a great number of houses listed across the country. As on overview, the Internet is a highly useful tool for getting some kinds of listing information, but the web doesn't even come close to doing away with the need for an agent. Not all the sites that you'll be looking at are updated constantly, and for that reason you can contact a place for a viewing that's already under contract.
The point here is that's there is no good substitution for a real live person in a real estate office that can talk you through the property as you physically walk through. While virtual tours are popular to get a first impression, it's impossible to open closet doors and stand in a room to get the feel for the place online. The National Association of Realtors is a good starting point and a fine way to use online resources to start the journey toward buying a house. Remember, if you don't have the URL for the agent or company you're looking for, and the URL is just a fancy way of saying website, you can always just type the name into a search engine like google and a list will pop up.
Remember too that finding an agent that will suit your needs is like looking for any other kind of professional-you wouldn't hire a painter to go through your home without first getting to know a little something about him-so it's perfectly fine to ask a real estate agent a few questions as well. Here things like references can be very important.
If possible it's a great idea to get a list of the other customers that the agent you're considering has had and then maybe even have a talk with a few of them. In an unguarded environment that could even include a visit to the person's house that the agent sold them, you can find out a lot about how that agent deals with other people and how they've worked in the past to get a home sold.
Remember that real estate agents are trained professionals that have written a series of examinations that qualify them to call themselves an agent. That doesn't mean, however, that there won't be some that are better at the job than others, but picking one that's right for you will help provide a personalized touch that looking for homes on the Internet can't provide.