Alien Skin BlowUp (about $200)
When your pictures need more after-the-fact resolution, you'll often get better results with a specialized plug-in than an all-purpose image editor. Through an unintimidating interface BlowUp lets you size up CMYK, LAB, Duotone, and Grayscale files, in addition to the usual RGB, with smooth, sharp results.
Imagenomic Portraiture plug-in (about $170)
Healing, softening, warming, and otherwise retouching portraits in Photoshop can be arduous, especially if you have a lot to do. Imagenomic's time-saving plug-in does an excellent job of automatically smoothing and toning skin.
onOne Photoshop Plug-in Suite (about $400)
The go-to company for great Photoshop plug-ins, onOne makes Genuine Fractals (the king of image interpolation), Mask Pro (for easy isolation of complex shapes), PhotoFrame Pro (for adding and manipulating borders), and Intellihance Pro (for fast image improvement). This new product gives you all of them as a plug-in suite for Photoshop. (A version for Elements users is available for $60.)
Photoshop Elements 5.0 (about $100)
For photographers new to image editing, this program is a good place to start (if you eventually want to learn Photoshop) and a fine place to stay (because it offers many of its big brother's best features). This much-enhanced new version even has an introduction to Curves.
American PHOTO Editor's Choice 2007