I love well-designed software. Minimal design, intuitive interface, with a very clear purpose. Delicious Library is a work of art. Not only does it clearly demonstrate its purpose (see screenshot), but its amazingly easy to use, from keyboard shortcuts to its webcam barcode reader.
In about an hour, I scanned in all the books I keep in my little studio apartment (141). It automatically references the books synopsis, details, reviews and, in some cases, an image of its cover. My only complaint: better ability to find the cover art, but I’m sure this will improve in upcoming versions. (This was the only section of my digital library that had an overwhelming majority of covers; much of the rest have a pure textual cover, as in the lower left book in this image.)
Another fun example is recommendation engines. Here’s YouTube calling me out for my love of RSA, Phineas and Ferb, and TED:
And lastly, I recently made the switch from Firefox/Safari to Chrome. Everyone knows Chrome, so I won’t elaborate here; simply, its interface and speed (eventually) won out over Firefox’s extensions.