I've just been checking out Apple Keynote presentation software, and I'm finding it's useful for a lot more than persentations. It has the capability of doing a lot of what Hypercard used to do. For the younsters here, before the coming of the internet there was quite a circulation of public domain material--a lot with educational interest--created with it. I've started a site to share Keynote presentations in a similar way and have an interesting mathematics oriented one of my own there. It is a start on a kind of interactive handbook of mathematical formulas, definitions, and relations. I'm offering it free of charge as contributeware. If you use it and like it, you are honor system bound to contribute something to it. If you look at my pages, you will find this won't be hard to do, and it might even be a good student project. But the site is in no way just to promote my own presentation. Mainly it's to volunteer to maintain a list of links to presentations that others have done.
Unfortunately, this is not for everyone, because you need to have a Mac and Keynote. Yes, Keynote is sort of compatible with Powerpoint, but some of the best stuff you can do with it--the things it can do that Powerpoint can't--won't export properly, so if you want to join in this game, you really do need to have a Mac and have Keynote, but Keynote is quite cheap, and nowadays Macs are no longer that expensive, either.