Rulers "contains lists of heads of state and heads of government (and, in certain cases, de facto leaders not occupying either of those formal positions) of all countries and territories, going back to about 1700 in most cases. Also included are the subdivisions of various countries (the links are at the bottom of the respective country entries), as well as a selection of international organizations. Recent foreign ministers of all countries are listed separately." This is vast. Be sure to check out the chronicle of relevant events, eg December 2003, leadership changes from all over the world.
And on that subject: Electionworld lists the results of, what else, elections around the world.
(This is what the internet is about. Great stuff. But next, at a certain point you want to give these guys a CMS, get them producing structured data that can be syndicated outwards wherever it needs to be, and just see what happens.)