12 Top Notch Online Presentation Tools from SitePoint Collage - A Presentation Tool for Teachers Online Presentation Tools for the Classroom from LiveBinders Top Five Online Presentation Tools from Technology & Education Box of Tricks Presentation and Mapping Tools from Med Kharbach’ blog Presentation Tools from PBWorks Prezi    Prezi lets you bring your ideas into one space and see how they relate, helping you and your audience connect. Zoom out to see the big picture and zoom in to see details — a bit like web-based maps that have changed how we navigate through map books.  Seven Amazing Back-to-School Presentation Tools from Moyea What are Presentation Tools from Mikogo  Web2.04u2use – Click on Presentations

Presentations: From EdTech Toolbox
Bubbleshare - your photos, your voice, your story - narrated slide show online
Capzles is a free web application that allows you to combine your photos, videos, blog posts and mp3s into rich multimedia storylines.
Glogster - create online posters, media rich online posters that can be shared online or embeded onto wikis.

Myplick is a free service that lets you share and embed presentations online.  Formats supported are powerpoint, pdf,  and openoffice odp. 

Prezi is a web application that allows you to create stunning visual presentations. Think PowerPoint meets mind map.

Showbeyond - presentation editor
Slideshare allows you to upload and share your PowerPoint presentations. Presentations can then be embedded into blogs or wikis.
Sliderocket - create stunning looking powerpoint style presentations, viewed or shared online
Slideroll - create presentations from stills
Soapbx - create free public presentations online