Sometimes you forget how cool a tool is until someone else sees you use it and they remind you it kicks butt. I had that experience this week when I added the preceding alert dialog box to a users AutoCAD screen after fixing a problem for them when they were not at their desk.
The really cool thing is you can add these dialogs simply by typing them in on the command line. In the screen shot below you can see that you start with (alert "then put your message in quotes and close with a" ). To get a new line in the dialog just use a backslash followed by the letter n.
These boxes can also be called in lisp routines and macros forcing users to click OK before proceeding. I like to use this when they are about to do something that cannot be undone, something that will take a long time, or something that has great potential to jack a drawing up. Pretty much anytime you want the user to verify they know what they are getting into. Otherwise, they are awesome for messing with people. You can send messages like;