There's a web site that needs to exist (or, if it exists, I need to find it!).
When I lived in Chicago, 4 blocks from Wrigley Field, I knew exactly how and where to go to get the best tickets at the best price. At the time, all of the tickets that were being held by the ballclub for VIPs would be released to a certain ticket window, exactly one hour before the game.
That meant that you could show up at that window exactly one hour before any ballgame - no more, no less - and get great tickets to any game. At face value. Unfortunately, it doesn't work that way anymore at Wrigley. But there are a dozen other secrets like that for EVERY ballpark.
Real fans know what section to sit in. They know which concession stands have the shortest line. They know the only place in the ballpark to buy freshly roasted peanuts in a brown paper bag.
And there is no reason that everyone shouldn't have access to their wisdom. I travel the country going from ballpark to ballpark, and that kind of information would be incredibly valuable! So here's my suggestion for an enterprising entrepreneur out there:
Take the ESPN stadium guide linked above as a starting point. But turn it into a park-by-park wiki, topic-by-topic that can be contributed to by fans. And monetize it by letting a ticket broker sell seats from the site ... but DON'T let them spam the site. They get to sell tickets, but no messaging. Only real fans get to post ... just like wikipedia.