Even then, you can make a good approximation to their actual timezone using IP geolocation. Then there are the pseudo-dropdowns where the user starts typing the

Even then, you can make a good approximation to their actual timezone using IP geolocation. Then there are the pseudo-dropdowns where the user starts typing their city name (or a prominent city in their timezone) and you look it up on the fly. And then you package that control up as a module to share with other projects that you write :)