We are currently running a mediawiki for our developers and most developers are not adding entries if they find something to document. Instead the mail it so a list containing all developers and most often I add the entries. I just thought adding something like score, achievements, badges or similar could add motivation but I cannot find a extension for media wiki. Is there such an extension? Is one of these recommended? Funny fact: Currently I think the StackExchange system would fit much better but we need it internally ;)