Unsatisfied with your identity in Mac OS X? Bothered that the person being asked to provide an administrator password isn't really you? You can always open the Accounts pane of System Preferences and change the Name field that holds your full name. But the Short Name field below it remains frustratingly immutable, even after you click the lock icon, making you think, perhaps, that Mac OS X is being unnecessarily over-protective.
This is backwards. Your full name is what you can't escape, the one inscribed on your birth certificate. But short names, whether they're chosen, assigned, or merely accidental, are more malleable. My late grandfather Orville was known to his friends as Barb, a seemingly inexplicable nickname for a powerfully built farmer who could fix electric fences without turning off the heat. It was finally explained to me that it was short for "barbarian," a reference to his football and boxing prowess at Cornell University in the 1930s.
Had Grandpa accidentally set his short name in Mac OS X to "orville" when he would have preferred "barb", the ChangeShortName utility from James Bucanek and Dan Frakes would have come in handy. It is possible to change a short name in Mac OS X with appropriate incantations at the command line and gestures in Apple's NetInfo Manager, along with edits to configuration files. But it's a tedious process involving so many steps that not even are complete. It's also prone to errors: if you mess up, you're looking at significant recovery efforts.
 makes this process far easier and more foolproof by encapsulating all the steps necessary to change an account's short name. All you have to do is select an existing name, enter the new name, and click a button. Plus, if you've tried and failed to change a short name on your own, it can also repair some of the damage. It requires Mac OS X 10.3 or later, and is free, though donations are requested. Even with ChangeShortName, changing your short name isn't the sort of thing to do lightly, so be sure to read the included documentation before using it. It's a 424K download.