Slideshare.net – upload slideshows and embed for free
Slideshare is a great service if you need somewhere to store slideshows online for free. you can upload powerpoints as shows or pdf files. Other programmes (e.g. mac) need to be uploaded as pdf.
Shows are then processed and can be embedded to blogs, wikis or webpages and, if you allow it, they can be downloaded by those who view them. They can be tagged and can also be viewed fullscreen online. It’s pretty much the YouTube of powerpoints.
Here’s an example (Photosynthesis* for IBDP Biology):
*edit – I had posted Cell Respiration, but deleted it by accident from the Slideshare account. Be careful – there’s no ‘are you sure?‘ box when you hit delete!