Domain parking is another online business that some people get into. It pays peanuts in most cases but there is a lucky chance to be able to profit good.

This involves buying good keyword domains and parking them with a company. Basically you depend traffic to click on the ads on this un-developed site to that company and they will pay a PPC price to you. You don't really make much but you can promote the site as if there is one for the domain and buy domain by the hundreds. This is probably the most boring online business you can have, but the least risky and least effort can be put into the domains.

There isn't much to learn if your considering to get into this. http://www.sedo.com is the top ranked domain parking website in the world and has been for a longtime.