Well if you find yourself with a dirty monitor and no window cleaner I have a solution for you. Just dilute a cap of rubbing alcohol into some water and get yourself a couple paper towels and your good to go. Just cleaned my LCD and its good as new, you'll want some kind of glare on the screen so you can spot the smudge marks. Be sure to TURN OFF THE MONITOR.
Enjoy your new sexy clean monitor.

I'm sure some, if not most, people already know this but I figured it'd help out those that dont and hate having dirty monitors.
Share your ways to get a monitor clean besides the one above. This thread can be a resource