I discovered empressr.com last spring. The format is similar to Powerpoint (or Keynote for the Maclovers out there), except it is more streamlined, and it is cloud-based. It also allows for creation of audio, video and photos within itself, as well as allowing files to be imported into your library.
Is it free? Of course! Is a download required? Absolutely not!
I am a MacGirl, and had been primarily using Keynote for years. Yes, Keynote will open Powerpoint files, and yes, it allows you to export from Keynote to Powerpoint format, but it never works perfectly in either direction.
I have long had issues with students using a version of Powerpoint that is newer than Powerpoint 2003 (which is what our school computers have) and the files are incompatible.
Another benefit to empressr -- NO MORE FLASH DRIVES!!! I have no particular beef with flash drives, I just always seem to lose them, which defeats their purpose.
No more need to remember to email myself a presentation I created at school, because it's in the cloud!
Downsides? It is definitely more bare-bones than Powerpoint or Keynote, but I acually find this to be an upside when working with middle-schoolers who often tend to over-focus on aesthetics to the detriment of content when too many options are available to them. Also, I have been unsuccessful at embedding empressrs into wikipsaces pages, so we have to settle for a link.
My first attempt at using empressr with studetns involved having an empressr presentation as an option for their family tree project (other options: paper poster, popplet, prezi, or glogster). I had only one student choose to use empressr, with little or no guidance from me -- technologically speaking. The vast majority of questions I was answering were content-related, or research-related.
Bottom line, I am impressed with empressr.
Here's an example:
What do you think?