Usually when I see hardcore bands they bring a few lights along, especially if it's a small show. Most of them will have a macbook present and they don't have any song clips or anything, so i figure the programming comes from the laptop? How do you do this and what does it entail?

AnalogMan Stereo Chorus
Barber Tone Press
Way Huge Supa Puss

I met a guy after this gig who programs all his lights through midi on his mac. Sounds complicated but it was really easy.