It is a known fact that many big website use multiple domains to sell the same products or services or even to advertise for them. The theory behind this is is that customers or even normal surfers go through many websites before they make their purchase. Using multiple domains increses the chance of getting a wee bit more of this traffic and eventually more sale if configured well. Lets look at a few things to do in order to set this up.
Buy the domains:
When looking to but domains to set up your site look for keywords the your targeting. If you deal with electronic items you could have your multiple domain project working around mobile phones . The domains should sound like mobile-xyz.com or x-mobile.com. Try to avoid making the domain look spammy. The more dashes you have the spammier it looks.
Build a fishing net with the domains:
If a person is searching for a place to buy a mobile phone for example, of a certain brand in a certain geographic location, if he is a smart buyer he will run through a few site before he makes his lays down the bucks. This is where we set out the net. 3 – 4 identical sites with a few design changes and wham your in. This sure increases the odds from 1 to 4 of the customer landing on one of your sites. This would increase traffic. You can play with the prices on the other site or even throw in discounts to eventually lead the customer to your desired site.
PS: Google web optimization is a good tool to use to check how people react to pages and do a kind of a-b testing.