If you have any need to batch convert and resize images I urge you to check out a recent how-to article by Jim Tanous of The Mac Observer. Jim takes you through all the steps necessary to do this, using Automator. Automator is part of your operating system. This process works in Snow Leopard and Lion, as well as Mountain Lion.
It is so easy and Jim explains it beautifully. Personally, this tip saves me an hour or more a day and I know there are others who will benefit as well.