First, bring a nice bottle of whiskey in to your office and put it on your desk. Make it widely known that the bottle will not be touched under any circumstances UNLESS someone asks you to do something that wasn't already on your plate. Every time anyone asks you to do anything you weren't already planning on, you will take 1 standard shot, then do the task to the best of your ability after however many shots you've already had. For particularly annoying users/coworkers, you may, at your discretion, take one shot as soon as you're interrupted, and one just before you start their task.
I call it Driusan's Rule. I predict an inverse relationship between the number of bikeshed requests you get and how widely publicized Driusan's Rule is amongst your users/coworkers. If I'm mistaken about that, then I predict their requests won't bother you as much, at least.
The more widely publicized/used this policy becomes, the more likely it is to become standard industry practice. So tell your friends.