If you want flickering lights....you CANNOT go wrong with i-zombie. It may be expensive, but trust me you will not regret it! I run over 36 par 38 can lights with gel colors off of my i-zombie. It is EASILY the best purchase I have ever made. I run it off my ipod, which is loaded with nothing but thunder and lightening sounds and it is the BOMB. OMG it is so cool. Get the CD too!
http://www.i-zombie.com/