One of the few things I like about Powerpoint is its ability to print large posters. You can do the same thing in Keynote 09, but it isn't immediately obvious how. Select a new file with whatever screen-size you want. Next, click on the Document icon (at far left) in the Inspector. On the Document tab, select Custom slide size... from the Slide Size drop-down. Enter whatever size poster you want, in pixels. Figure that the printout will be at 72 pixels per inch, so a 4- by 3-foot poster would be 3456 x 2592 pixels. When you're ready to print, export to whatever file type your poster printer accepts.