Plugin or javascript?

I’ve been thinking of a feature I’d like to have on one of my sites, but I don’t know exactly how to go about putting it into action, whether there is a plugin available or whether this is a javascript kind of thing.

Basically what I’d like to have is a “This Day In History” kind of thing in the sidebar, where the current date shows up, and then each day, the date automatically updates, and the list of events from history updates as well. I’d want to list my own events, of course, but not quite sure where to start with all this.

Any pointers? Thanks! 🙂