Attached Link: http://www.dexfx.com/Effects.htm

I've also used the grouping behaviors before -- my flying saucers attacking San Francisco (see the link) have some side to side motion (yaw, I guess). Then, I group the flying saucer, move its hotpoint WAY off center of the object, then rotate the group to get the nice circular flight path. Very useful technique that I think I read about first here in 'rosity way back when Clint was the RDS moderator. - Dex