dialti.me is a super simple, streamlined evolution of Sundial. It's designed to solve the same problem—converting US telephone numbers to timezones—with less faff and cleaner design.
Sundial is lacking daylight saving time support, lives among a cluttered page on my personal website, and despite being useful it felt awkward to use.
I created dialti.me to rectify these problems, placing it onto a simple site of its own and adding DST support. But in order to give myself the motiviation to revamp the tool, I created it using different technology: rather than use a couple of hacky Python scripts, I instead used Java servlets, JSON and the Google App Engine. It taught me a lot about the simplicity of the App Engine platform and the relative complexity of Java versus Python. All-in-all, it was a great "weekend" project.
Like Sundial, dialti.me is still freely available for public use. I still plan to add support for international numbers outside of the US, too—though this time I'll endeavour to avoid a redesign in the process.
Usage: http://dialti.me/number/%s
where %s is the telephone number to lookup.