Semantic MediaWiki: Toward smarter wikis

Amazingly, they thought of that. At one point there was different syntax for annotating links and values, but you've always been able to specify the type of a property using the special property [[Has type::Number]] (for population, other types include Date, String, URL, Geographic coordinate). See http://semantic-mediawiki.org/wiki/Help:Properties_and_ty...

SMW annotations make statements about wiki pages, and much of its workings including user properties like [[Property:Has capital]], live in wiki pages. It's oddly powerful.