The market-driven principles of the domain trade mean that a domain is only worth as much as the buyer is willing to pay. It is for this reason that criteria such as market potential and usability play such central roles in determining prices. Values can change at the drop of a hat. The price of a domain that was once of little interest to anyone in years past can skyrocket once, for example, a newly founded company takes interest in that same name.
In order to register any domain, you must provide certain personal information that you may not wish to be publically searchable in the Whois database. Signing up for WhoisGuard is a great way to keep your registration data private. WhoisGuard acts as a "shield" for your searchable information, displaying the address, phone number, and email of the domain registrar (Namecheap, e.g.) instead of your own. Keep in mind that WhoisGuard is an optional security add-on that must be renewed separately when you renew your domain.
If you have a web site, you should seriously consider registering your own domain name. A domain name is a name like "thesitewizard.com" or "thefreecountry.com", which you can use to refer to your website. Note that you do not have to be a company or organisation ("organization" if you use a different variant of English) to register a domain name. Any individual can do it too.
Many registrars reserve the right to revoke your domain name for specific reasons, typically if you use the domain for illegal purposes or purposes deemed unacceptable (such as spamming). Many contracts contain a clause letting the registrar delete your domain name for no apparent reason. The implication, of course, is that the domain name is the registrar's, not yours.
While looking at domains, you might come across the name "ICANN" -- the Internet Corporation for Assigned Names and Numbers. This organization accredits some registrars that agree to a set of operational standards, but ICANN accreditation isn't required to sell domains, nor is it necessarily a sign of a company with good customer service. In fact, ICANN plays no role in the sale of many top-level domains, including country-specific domains.