I've just been asked to put together “a little hours open-and-closed app” for the home-office of a retail company ... and I can plainly see that what it really is, is:   a scheduling application. Standard hours open/closed, holidays, and recording of exceptions when a store had to close early or somesuch.

In other words, an application that must have been done countless times before. Therefore, in the spirit of “laziness is a virtue,” I'd like comments on what might be a suitable web-app that can be dropped into an existing (increasingly Ajax-oriented) intranet.

We are using the ExtJS 3.x framework to build user interfaces and the users are by now quite accustomed to that. So, I'd love to find a pre-existing application that uses the same interface front-end. The intricacy ... the boring, repetitive, and tricky intricacy ... of “all that back-end design and coding” is what I would really like to avoid. Solutions must be open-source (or software-as-a-service).

Thoughts? “Been there, done that, and this is what we did?”