1) All visits to the mound should be banned, except for the manager visiting to take out the pitcher, which should be preserved only on tradition grounds. Otherwise, no one should get out there and delay the game. If the signs are mixed up, the catcher can revert to 1 for fastball, 2 for a curve. If the pitcher needs to know who's covering second, the second baseman or shortstop can point to himself. But it's a travesty that Jose Molina can--if memory serves--visit the mound six times during the fifth inning of Game 2 of the ALCS and contribute to that half-inning alone taking half-an-hour to complete. Baseball is the best of all sports at building tension, but there's way too much needless delay.
2) Balls and strikes should be determined by lasers (only those we can spare from volcano-lancing, of course). There's no excuse for allowing the imprecision of a home-plate umpire in the 21st century.
3) Each manager should have one or two challenges during the course of the game to get calls on the field reviewed. Please don't tell me about the flow of the game (see point 1). As someone pointed out the other day, bad calls tend to even out over 162 games but they can have a disproportionate impact in October (or November, but don't get me started on that).