10 to 30K Volt Flyback Power Supply:

Flyback Circuit Provides Isolated Power Conversion: 01/07/99 EDN-Design Ideas  / PDF contains multiple circuits - scroll to find this circuit.

Ignition Coil / Flyback Transformer Based High Voltage Generators: This page gives my thoughts on how to use a car ignition coil or Flyback transformer as a high voltage generator. The objective is to produce as high a voltage as possible, with as high a power throughput as possible.  

Output Adjustable Flyback Converter:

Single Transistor Flyback Driver: