This page hosts a slowly growing collection of tools and services available for use by the general public (or, more likely, me).
dialti.me allows you to convert US telephone numbers to timezones. Want to make a call? Don't know what time it is at the other end? Enter any US telephone number and find out.
Sundial has now been superseded by dialti.me.
.My next big thing. It's not quite ready for primetime yet, but it's coming soon. (For certain values of “soon”.)