Yes, I finally thought of one. It occurred to me just now:
Each and every one of the 50 states should levy a tax, at a rate of 100%, on all incomes deriving from the federal government. Said tax to be applicable both as to residents and, a la California's habit of taxing out-of-state athletes who play professional sports games in the state, to activities within their jurisdictions.
Effect: If you want to be a federal employee and make any money at it, you can only live, and you can only WORK, in the District of Columbia.