I purchased my Canon S3 IS camera back in September and I've thoroughly enjoyed using it. It's fast and easy to use and the pictures it takes are a few steps above the old 3-megapixel Fuji point-and-shoot I was using. The image stabilization allows me to shoot hand-held in situations I'd never dream of shooting before, and I can tweak the camera to get shots I couldn't do before.
I stumbled across a site with S3 tips: Bagelturf. I can't tell who the blogger actually is but he has a Mac and he has an S3 like I do. Check out his tips on things like focusing on tricky subjects and focus bracketing are especially good.