Wiki text can be daunting to the casual contributor. SocialText and Wikia have been working collaboratively to introduce the type of WikiWYG editing found on the SocialText site to MediaWiki. For an example of a page showing wikiwyg try this: Creatures_3 - make sure to turn on wikiwyg editing.
Make sure to enable wikiwyg using the left-hand navigation bar before editing. On pages where wikiwyg editing can be used for section editing, you'll see a link for "Wikiwyg edit". If the page has any wikitext that the wikiwyg parser doesn't understand, then you'll see a link for "Quick edit" (for instance, here - make sure to turn on wikiwyg editing).