The only way to truly sound trigger is with time code unfortunately, and that means quite a bit of money. Midi is a kind of sound triggering, but only works off of certain notes. It is like a poor man's time code (no offense, you can do some really awesome things with midi triggering, just can do that much more with time code). Once I get ESP Vision, I think I am going to post a few videos of what you can really do with syncing via track/time code. Some good stuff is out there on YouTube as well, Soundlight comes to mind. Search "Light Show - Are You Gonna Be My Girl - Jet" and "Light Show - Tank - The Seatbelts". Those light shows where programed with an ETC Obsession 750 using SMPTE time code. So you get an idea of what can be done.
Now, would I do something that busy for a dance/band, no because they would just be staring at the lights the whole time. The point is, you can see how you can sync things really easily for great effects. Remember, less is sometimes more and much more powerful as well.