If you've ever tried to work with small images, like the kinds generated by cameraphones, you know how frustrating it can be to turn them into something printable (or in some cases, easily viewable). Most image editors make an attempt to smooth and sharpen, and some add a bit of "noise" (random data, which, counterintuitively, can make an enlarged picture look a bit sharper) to enlarged images,. But I haven't seen any of them do as good a job as SmillaEnlarger (free) can do at taking tiny bitmap files and turning them into usable, full-size images.
To test the app, I took some screenshots of standard-sized application and file icons in Windows. A typical icon image is 32 by 32 pixels when displayed at desktop resolutions of 72 dpi--pretty small and, when you enlarge them, they look pretty chunky, like billboards made of Lego bricks. SmillaEnlarger's algorithm does a remarkable job of turning even an incredibly minute bitmap into something close to a blurry snapshot. While this is the full extent of its abilities, you might want to keep SmillaEnlarger in your digital imagery toolkit for a photographic rainy day.