[Puke]

someone brought up mirrors, to target or deflect lasers, a page or so back.

while that works for low powered lasers, i believe these days most are directed by magnetic fields, much like the particle guns in side a television tube. the problem with mirrors - especially on more powerfull beams - is that they actually are not all that reflective. even with a reflection index of about 90%, which is nigh impossible to create and maintain, a laser will quickly damage or destroy the mirror. most of the problem lies in that mirrors are not all that reflective, the rest of the problem lies in that the reflectiveness is highly subject to damage and is hard to maintain (frequent polishing, must controll exposure to elements, temperature...)

somone else mentioned laser propulsion for space vehicles - i believe nasa recently flew the first small craft (model airplane) powered entirely by lasers. maybe a week or two ago.