Ahead is a new site that is similar to Prezi. You can use Ahead to create presentations using multimedia resources and zooming and panning effects across the screen.
It is web based and uses Flash. The free version gives you 300MB of storage, public only presentations, and unlimited "spaces" (presentations).
It is another resource that you can use to create interesting and engaging presentations. There are some great tutorials on the site, and lots of examples you can look at.
Prezi - the zooming presentation editor