The definition of "domainer" on Wikipedia redirected to "cybersquatter" for a long time. Recently an article has shown up in for review (and has also been proposed for deletion). You can see the article at Wikipedia.org and you can discuss the article (and vote on whether to delete it) here. The article is spammy in places. There is a link to PremiumDomains.biz that appears to be self-serving (and may be counter-prodictive). Please consider editing and improving this article, but please refrain from spammy links to your own sites if you do this.
Because the article may be deleted I am excerpting below muchof the content that appeared on 8/10/09 at 8:30 pm:
Domaining is the practice of monetizing Internet domain names using a variety of methods and strategies. These approaches may include website development, minisite creation, affiliate marketing partnerships, domain forwarding services, domain name sales and leasing, the selling of direct sales lead via customer opt-in, the inclusion of paid business directory listings. A popular strategy to monetize domain name involves creation of websites displaying pay per click advertising. These practices often lead to domain name speculation, but the latter is also a preferred activity in itself for the majority of domaining practitioners. An individual who engages in domaining is referred to as a domainer.
The underlying opportunity for profiting from domaining lies in the limited supply of simple, memorable names within the most popular top-level domains (TLDs), most notably the TLD COM. Major Internet service providers have been known to practice domaining by benefiting from mistyped domain names in web browsers, and redirecting the invalid domain names to advertising sites created for this purpose.