Recently I've put a few of my PowerPoint presentations online. It used to be that the best way to do this was though sites like SlideShare or other similar sites. But with the new 2010 version of PowerPoint you can save your slideshow as a video that can then be uploaded to YouTube (or any other video sharing site).
The basic process is simple. You click on the "File" tab in PowerPoint 2010 and then click "Save and Send" from the list of option. Click "Create Video" under File Types and then click the "Create Video" button on the right.
However that assign a standard amount of time to every slide in your presentation. If you have animations and video in your slideshow, you'll want to use custom timings for your slides. The way to get those is to rehearse.
Click on the "Slide Show" tab and then click "Rehearse Timings." When you do, you'll see your presentation on the screen. Press the Right Arrow when you want to advance the slide. When you're done, accept the dialog indicating that you'll use these timings and save them with the presentation. Click the "Save" button in the upper left and then you can go back to creating the video knowing that your slides will have the right timing.
If you want to record narration with the slides, you can use the "Record Slide Show" button on the Slide Show tab. This allows you to speak your piece while you click through the slides. Both the audio and the timing will be saved with the slideshow and then you can include them with the video you create.
Even though it's really cool that you can turn your PowerPoint into a video, Microsoft will only create videos in the Windows Media Video (WMV) format. If you want something a bit more friendly to other platforms, you can use a video conversion tool (like this one, or this one) to change things into a format other than WMV.
Below I've included the YouTube videos of some of my presentations. What do you think?