Intensify is a new Mac app designed to dramatically enhance your images without requiring you to have deep knowledge of editing and adjustments. I would put it solidly between the iPhoto's editing tools and Photoshop.
Open Intensify, then open an image and explore the presets designed by pro photographers. You'll find options that go way beyond iPhoto and other simple image editors, yet the changes are easy to apply. If you can't find a preset you like, there is a full range of adjustments that work in real time for things like contrast, exposure, vibrance, structure, details and shadow detail.
Like all image editors, you can be as subtle or as far out as you like. Intensify opens both RAW and 16-bit images. I found the app and its adjustments best suited for landscapes, where editing can make a powerful difference.
I tried some images taken on a recent trip to Bryce Canyon in Utah, and was pleased with the results. Supported file formats include RAW, TIFF 8- and 16-bit, PNG and JPEG. The app lets you see your changes side by side with the original as you work, and in every case I could really improve on my original. The structure slider gave the rocks more detail, and I painted a mask over the sky and reduced the exposure to bring out more sky colors without darkening the rest of the image. Intensify supports multiple layers so you can add effects on top of your original and easily enhance or remove them.