I tried 3 of the options, thumbstacks did not work. I tried to google it and it still did not work so I think it is a problem with the site and not the link.
Zoho Show is basically an on-line application of Powerpoint. It is simple and can not do animations.
I posted a powerpoint that I already had created on a year I spent teaching English in China. I made it in Slideshare. It took two tries. The first time took almost an hour before the website told me there was a problem. The second time worked well. This site is good for posting existing presentations, but you can not create any on it. It does have a nice feature that you can add music to your show.
My favorite was Slide. I created this display of a concrete fire pit top that I made. This site took a couple of minutes to upload the pictures. Then it had many fun effects to choose from and skins can be added.
Adding these shows to my blog was super easy and they have links to add them to about any on-line application you can think of. I could use these to have students make slideshows of their projects. I could add video of a balsa tower breaking or the launching of a pop bottle rocket. Students could also make their own slideshows on a topic.