If you have nothing else to do, look about you and see if there isn't something close at hand that you can improve! It may make you wealthy, thought it is more likely that it will make you happy.
Just wondering if Google take into account the length of time a site has been at say the top position for a certain keyword when deciding on search positions?
I mean if there was a site that had been the first search result for a given keyword for ages, would you be able to knock that site off the top spot if yours was SEO was better for that keyword, or would it take longer than usual?