It was once the sole domain of nerds and academics, but now just about anyone can have their own website. If you’re also a dungeon master, you may not only enjoy maintaining a website detailing your game world and rules, but find it a practical addition to your game. Modern web-based content management systems exist which, once installed, allow you and your players to collaboratively edit pages with surprising ease.
Roleplaying gamers have been keeping websites for some time now. One dungeon master keeps a website to publish his house rules, along with new game material (in this case, new rules for fencing). You might also use a campaign website to keep a log of the game’s storyline, session synopses and character sheets, or to collect information on your homebrew campaign setting. I know of one DM who offers his players bonus XP for contributing. A campaign website can also be a useful way of publishing homebrew game material, from feats to entire prestige classes.
Modern open source web software makes a website like this quite straigforward to set up. One such piece of software is PmWiki. PmWiki is more modest than Mediawiki, the software used to run Wikipedia, but is simpler and better suited to sites with a small number of editors, like a D&D site. You will, however, need to be comfortable with uploading files, and require a webhost that supports PHP.
If that’s too hi-tech for you, Google Page Creator offers webhosting and page editing. However, it doesn’t offer the functionality to let your players edit your pages - you may want to look for a friend who knows web stuff to assist you with the setup of your wiki software.
The important thing, as is it often said about dungeon mastering as a whole, is to make sure that your campaign website is something enjoyable, not a chore.