Domaining is the activity of buying and selling domains on speculation and is often compared to the Real Estate business. Once domainers buy domains, they park their websites. Parking refers to developing content in the form of Web links and ads, to generate income and increase the value of their domain name.
Domain parking is also used by domainers in an effort to differentiate themselves from cybersquatters, who buy domain names just to sell it to the someone who owns a trademark contained within the name at an extremely inflated price.
One of the most famous Domainers out there is Kevin Ham. The son of Korean born immigrants in Vancouver, BC, Kevin trained as a doctor but after discovering the power of the internet in 2000, he got into the domaining business and has since collected more than 300,000 domains. As of May 2007, he owned God.com and Satan.com. Combined with this other business interests, he generates about 70 million a year in revenue.
Kevin has an unlikely partner in his ventures. Cameroon. Yes, Cameroon. He chose to work with Cameroon so that he could buy .cm domains and the reason behind this is that many people mistype a web address and instead of going to .com, they land up at a .cm. Try going to beer.cm and you will be redirected to agoga.com which belongs to Kevin.
If you plan on becoming a domainer, here is one tip. Stay away from domain names that have patented words in them.
Some of the interesting resources to read up on domaining are: http://www.domainersmagazine.com and http://www.domaining.com