[Hutch]

The general avoid flash/java/frames rules have been mentioned... Of course, don't do anything obnoxious (read: bright backgrounds, too much animation, etc.) For ease of maintenance, avoid tables as they are just a mess - CSS is definitely your friend for positioning as well as styling.

Good things to do: dynamic content (news, that sort of thing), lots of pictures, content such as animations from previous years. Just make the site generally helpful and informative, and don't worry so much about winning an award - the most important thing is that everyone will like your webiste, not just judges.