Simple Spark Gap
This is a really simple spark gap that can be made in minutes. The two brass electrodes are cheap kitchen cupboard doorknobs available at any hardware store (get the solid brass ones, not the plated iron ones). The knob on the right is drilled through its centre and brazed (though solder would work) to a copper tube, which is in turn connected to my 120PSI, 16cfm air compressor. When air is blowing over the left electrode, you can actually feel the high speed air "sticking" to it - the electrode is completely encased in high velocity air, kind of like all those pictures you see showing how aeroplane wings work.
In operation, you can actually see the spark length change with alterations made to the air flow via a ball valve. I have tried many types of static gaps, and this is definitely better than any RQ/TCBOR/SUCKER gap style. The downside is most of us don't have a compressor, but if you do, give it a go.