App note from Analog Devices discussing bootstrapping its rail voltage to compensate operating range of an op amp. Link here (PDF)
When an off the shelf operational amplifier (op amp) cannot provide the signal swing range needed for a particular application, the engineer is faced with using a high voltage op amp or designing a discrete solution—both choices being potentially costly avenues to solving the problem. A third option, bootstrapping, can be an inexpensive alternative to these approaches for many applications. A bootstrapped power supply circuit involves a fairly straight-forward design exercise in all but the most dynamic performance demanding applications.