Reminder Emails

It would be nice if those that have signed up for an event could be reminded by email a day or two before.

Does anyone know how to make this happen? A 24-hour prior to start time reminder email?

That's not the answer you're waiting for, but theoretically one can open the event in Editevent view and (with or without changes) click Save.

Technically a reminder function is not really complicated I think. But one of the problems is that this function needs a user requesting a page (or a cron job). So there would be the risk to get no reminder because nobody looks on this site for days.
Also too many "background" operations doesn't make the user triggering them not really happy.