A tip, when writting a linear chromatic passage, try not to go in one direction for too long. It's boring. Ex. play 5 notes down, then go up. Zig-zag chromatic (not always a semi-tone either) patterns can be very lively, think flight of the bumblebee. I'm sure petrucci said something similar.
[Edited by noticingthemistake on 01-20-2004 at 04:26 AM]
"My whole life is a dark room...ONE BIG DARK ROOM" - a.f.i.