I wrote an web based to-do list at http://www.excusemenow.com a few years ago, it's live, but I haven't touched it. So it seemed like the thing to do would be to open source the code for the project so that others might get some use from it.
Fed up forgetting birthdays of your firends / relatives? Tired of setting up reminders plugins for all your different jabber clients? Zadolbator, being once installed at Jabber server side, provides THE ultimate solution! ;-)