I needed to round one corner of a rectangle in Illustrator today. This requires just a couple easy clicks in InDesign CS5. But in Illustrator this isn't so easy. Sure, there are various sneaky ways to do it without too much work, but it got me thinking about what the easiest way might be.
I'm convinced that the absolute easiest way to do this in Illustrator is with a free script from Hiroyuki Sato. Download the scripts (for AI CS - CS5) here, unzip them, and put the resulting folder somewhere you can find it. Then, whenever you need to round one or more corners of a rectangle (or any other shape, for that matter), select the corner(s) with the Direct Selection tool. Then choose File > Scripts > Other Scripts and select the folder containing the scripts. Select the Round Any Corner script, and you're done!
(While you're at it, check out some of the other cool scripts that Hiroyuki has written. I wrote about this previously here.)