You can get quite nice flashing effect if you build two of this type of circuit and attach them to different color spotlights. Both of the bulbs will then flash at different rate and you will get nice multicolor semirandom flashing effect. The starter should be a cheapo bi-metalic bulb type that would normally make a fluorescent light flick a few times before it lights. The electronic starters won't work for this application. Depending the starter type and bulb rating, the flas rate and randomness varies.
Some disadvantages however are bursts of RF noise generated as the neon lamps switch.
The starters typically have some kind of filtering capacitor in them, but this alone usually does not RFI may affect any radio mics or some sensitive audio equioments in the vicinity. The starters tend to burn out rather quickly as they are not intended for this constant duty. Fortuantely those starters are cheap, so rpleacing them is not that expensive unless the circuit is intended for constant long time use.