With Photopeach you can very easily create a slideshow of your pictures.
This site allows students under 13 years of age to sign up so long as a parent or guardian reviews and completes the registration process.
Slideshare is a site that allows users age 13 and over to upload presentations and documents to share online. Several formats are supported:
Presentations: pdf, ppt, pps, pptx, ppsx, pot, potx (Powerpoint); odp (OpenOffice); key, zip (Apple Keynote).
Documents: pdf, doc, docx, rtf, xls (MSOffice); odt, ods(OpenOffice); Apple iWork Pages.
This is an example of a Slideshare presentation (which is easy to embed in a WordPress blog like this one).
WolframAlpha – a little fun!
For a presentation with a difference try Prezi which allows you to create dynamic presentations which provide an overview and allow you to zoom in on any element. There are no individual slides, you work on a large canvas on which you can zoom in and out. You can create a path to show parts of your canvas in a particular order. Learn Prezi. For further links on Prezi see these Diigo bookmarks (clicking on the green links will take you direct to the website). Have a look at these examples of Prezis (it is possible to reuse any of these). Prezi’s terms and conditions state that the site is for users over 18 only, but it is possible for those over 13 to sign up – see these two frequently asked questions: