A "grid" is a great accessory to constrain the output of your speedlite into a nice tight pattern. This tutorial was initially released via the Strobist Blog last fall, and is a great way to use up those pesky political signs you find laying around all over the place after election day.
Step 1: Step 1
Measure the head of your speedlite and cut a strip of political sign to match the width of the speedlite. Mark plastic corrugated in 1" segments.