My favourite search engine recently released a way to create and add plugins to their zeroclick info box. There are some good examples and a starting guide in the DuckDuckHack website. I checked out their Ideas page and picked up something that looked useful and fairly easy to implement: parsing a crontab into a human readable output.
Implementing it took about a day, and showed me how insanely useful CPAN is. The DDG folks were nice enough to add unit tests and tweak the code a bit, and have now released it on their website.