cf/x photo mosaic is a highly specialized app to create high quality image-from-images type mosaics. It doesn't do anything else, but this one thing it does better than any other application available (and, yes, that even includes our own flagship 'alpha'). In addition to being blindingly fast, photo mosaic comes with special presets that help you create great photo mosaics even out of borderline images.
photo mosaic is incredibly easy to use: drop in a picture, choose a tile source (e.g., an iPhoto event), press 'Go'. A few seconds later you have a beautiful photo mosaic.
photo mosaic is fully customizable - from the way tiles are processed to the way that colors are matched. As its sister application 'cf/x mosaic', 'cf/x photo mosaic' supports variably-sized tiles, 'messy' assembly, up to 40'000 individual tiles, and high-quality output (up to 30 x 30 inch at 300dpi). And if you want to show off how the mosaic is assembled, just tell photo mosaic to create a movie - it does the rest. DV, HD, iPhone, iPad - just one click. Quality? Broadcast. Yeah, that good.
For advanced mosaic creators, photo mosaic provides highly advanced visual image analysis packages that helps you to tweak and perfect your source data base - and can even recommend the preset that will work best.
photo mosaic exports to most common image formats, mail, Apple's Preview App, Aperture, iPhoto, social Web sites, and even can directly set your desktop picture to your newest creation.