For competitions?
Maybe a "Best Article" competition, or a "Best Transition from Stub to Full Article" award (that could be determined by looking at the history of the article). Those would be simple to do, although for wikis that are still lacking in content it would be rather disadvantageous to them.
Maybe a community awards for the anniversary? Best members (I nominate tacopill), most helpful staff, most edits NIWA-wide, etc... Be fun, different, and wouldn't hurt morale.