I just finished creating a slide show using SlideRocket. I have used and taught Prezi and Google Docs, so I wanted to try something new.
I used the fake presentation and once it was imported (very easy) I added text, YouTube video and made a few changes. It was very easy with no learning curve. The icons are intuitive and there is a help screen if you need more info. Here is the URL if you want to look: http://app.sliderocket.com/app/sliderocket.aspx#o
I think online presentations tools are wonderful. There are so many great things you can do and import. No more "Death by PowerPoint". All we need to do it teach the students that they need to supply the URL for the site they found the information.
As for suggesting presentation tools I think any of these are great for the students needing them for class presentations. Some of them do need a little more time to learn such as Prezi, but depending on the time the student has and if they need a tool just to show their data or a full bells and whistles there are great choices on this list.