I looked at Prezi for an online presentation tool. It is a good free tool - I am used to using PowerPoint and I do think it is a step down from it. If you didn't have a presentation tool, this would work well.
I think Prezi offers some different choices in presenting information. I used this in college and have seen some very engaging presentations. This is a tool that I forget about and would like to try to use in the coming year.
I think that Prezi is a great option to use rather than PowerPoint. I like to give the students the option of using it when they do a Presentation. Some can figure it out better than Powerpoint.