My favorite way of generating a negative rail using more modern components, the inverting sync buck configuration, is especially maddening. The circuit's input, the positive voltage, is the regulator's VCC: so far, so good. The output, the negative voltage, is the regulator's VEE... which sounds fine until you remember these are single supply regulators and so that's their "ground". It's the regulator output that's the mind-bending one: it gets tied to ground! A switching node output, grounded, just does not look right.

It actually makes a lot of sense once you draw it out. The startup is the truly confusing bit, but fortunately it's only unstable for your brain. These guys are actually pretty robust if you can find a part that withstands the full voltage stress (|Vin| + |Vout|), which isn't too hard these days. Highly recommended for a production-quality negative rail generator. Just don't try and do it with a regular buck; synchronous controllers only need apply.