The most popular way to control the lights in the light shows is a DMX.
Good basic description of DMX is here: http://www.pangolin.com/LD2000/dmx-about.htm


===== What is needed for a good light show =====


==== DMX interface ====

  * good one seems to be ENTEC USB-DMX 512 http://www.enttec.com/opendmxusb.php ($69 - check ebay).. just bought one on ebay for $59
{{lasershow:dmx_usb.jpg}}

  * Here is a open source buffered DMX interface with 3 universes: http://www.oksidizer.com/electronic/spp2dmx/index_en.html

==== DMX control software ====


Windows: 

Entec Light Factory: http://www.enttec.com/lightfactory.php ($480/512ch) 

Bluelight http://www.innovateshowcontrols.com/x1_overview.php ($400/512ch)

DMX Desk http://www.geocities.com/ph_zone/DMX_Desk/index.html simple, freeware

Open DMX Theater http://dmxtheater.plekkie.net/index.html

FreeStyler (Good) http://users.pandora.be/freestylerdmx/

MagicQ http://www.chamsys.co.uk/

Axis DMX: http://www.axisdmx.com/purchase.html


Linux:

DMX4Linux http://llg.cubic.org/dmx4linux/ driver

Q Light controller, uses DMX4Linux driver http://qlc.sourceforge.net/ 512devices

==== Dimmer pack ====

  * Here is a small 4 channel dimmer pack Optima from bulbamerica on Ebay:
{{lasershow:opdm20.jpg}}