Territorial wars over particular webpages on wikipedia. This happens the most when a moderator feels that a particular page is 'theirs', and they feel they know best what should be on that page. Any moderator who consistently reverts a wikipage because they don't like the data that someone adds (even if it is valid), is fueling a wiki-war.
Dude, that moderator has been waging wiki-war on the global warming page! He reverted all the information I added, for the third time!