Flyback transformers are used to drive the large odd shaped coils surround the neck of CRTs in TVs and computer monitors. They operate in the 15 to 150 kHz range, and can be used to generate high voltages!
Uzzors2k decided to experiment with generating voltages high enough to produce arcs, driving the the transformers with a simple 555 timer. He tried several different circuits using the 555 first to drive the transformer in flyback mode, then later as a push-pull driver. Various input voltages were tried, starting as low as 5 volts and moving up to a direct mains powered flyback driver. He even experimented with coloring the arcs with salts and making magnet vortexes!
You can read more about flyback transformers and find all the details on this project at the Uzzors2k website.
Definitely a dangerous looking (and cool) prototype!