this is a good tool I think - allows you to share presentations and comment on them ( either by speaking or typing). Need to explore more - some of it is US biased but otherwise usable and free. Need to register
VUVOX allows you to create interactive slideshows and presentations from photos, video and music from Flickr, Picasa Web Albums, YouTube, Facebook or your PC. You can share them with friends, and embed them on your Myspace page, blog or website.