Most of the time I create these on the computer or small sheet of paper then project that to trace it onto the poster board (for proper spacing). Sometimes I use the computer (like the hypothesis, theory and law posters).
Some of my poster are what started my idea of Summary Sheets (fitting all of the most important information on one piece of paper).
What posters do you have? What should your kids know that they always seem to forget? What posters do you wish you could make, but don't have the time? What else would stop you from making your own poster?