I really like this idea, and have been meaning to code up something similar for a while. A few points:

* I would like to set lengths of time shorter than 15 mins. * If you visit a URL like http://timeslot.me/agendas/#day/2011-4-29 without being logged in then the interface appears, and slightly works. A redirect to the login would be better * As others have mentioned, drag/drop of tasks and length would be great * And a random idea: I would quite like to have a "repository" (todo list) of tasks with the length already set which I could drag onto a day.

With the drag and drop functionality I would happily pay a few dollars per month for something like this.