The full list is here:
http://wiki.project1999.com/Special:WantedPages
Generally speaking, a lot of zones have mobs that are missing pages, and may not even have links to them. If you just go to a zone and run around, you'll probably find mobs that don't have pages on the Wiki. These pages usually are pretty easy to add using Ravhin's page creation tools:
http://www.destinati.com/project1999wiki/wikiUtils.php
The same goes for obscure items you might find on merchants and the like.