Most/all common English words have already been registered as domain names in the COM top-level (by professional collectors like Digimedia or Telepathy.com if noone else). So have many combinations and obvious extensions of words. This is one sometimes-amusing way of finding new sites to read and absorb HTML formatting tricks from. Here are a few randomly-generated ones; reload this page to get some more.
(Note that while someone probably owns many/most/all of the domains pointed to below, that doesn't mean that they're all correctly resolved today, or that they all have HTTP daemons listening on them. But many will. Try and see! To see if a domain-name is taken, click on the little "NSI" or "all" by the URL, or go somewhere like this or (for more names but less info) this.)
www.[word].com; almost certainly taken
More complex; perhaps taken, perhaps not