For logged-in users, it would make sense to weigh the hot questions based on the user's cross-site browsing activity (taking account views, votes, posts, etc.). For users who aren't logged in or have had default activity, an average cross-pollination statistic could be used (again taking into account commonality of views, votes, posts and so on). (I'm not a statistician, I don't know what measure to use.)
With Stack Exchange expanding more and more to non-computer related topics, the hot question list is becoming irrelevant to more and more of the user base. Consider Joe Average human being (not Joe Average programmer), who's a German native, English-speaking hobbyist gardener and reader, parent, practicing Christian, manages his finances and keeps fit... What does Joe care about computer stuff, computer stuff, computer stuff, computer stuffcomputer stuff, computer stuff, …?