Of all the tools out there, I have found that Slideshare is one of the most useful. I love being able to upload my slide deck to Slideshare so I can use it anywhere and anytime.
It even saved my bacon one time where I was to give a talk, and the laptop provided did not have PowerPoint on it. So, because I always think about back up plans, I logged into my Slideshare account, and presented using the browser.
Even more powerful, is the ability to post your shows online as embedded objects in blogs, wiki's and webpages - extending your thought further than your normal audience of learners.
Who knows - Slideshare might even help with this: