SlideShare allows you to share a Powerpoint presentation with someone who doesn't have the program, or who would rather not have such a large file emailed to them. Once uploaded (which doesn't require opening an account), you send your recipients a web address, where visitors can flip through the slides in a scaled-down view, or in full screen mode as they would in PowerPoint. Alternatively, you can embed the presentation within your own website.
For new presentations, or the ability to edit online, consider Google Docs Presentation module.
(Macworld) | Cost: | Requires: Powerpoint or compatible software | For further info...

Hailed by its inventor, Ray Kurzweil, as the future of e-publishing, Blio is a new software platform specifically for e-books designed to run on any computing device, which unlike current e-book readers, replicates the appearance of the pages of original printed book as is, including colour and typography (unlike the E-Ink technology behind most ebook readers, which is black-and-white), while preserving the information as searchable text. In addition, it offers text-to-speech, ability to synchronize bookmarks, highlights, last page read) across different devices.
(Wired) | Cost: Free | Requires: Windows, iPhone or iPod Touch | For further info...

Now that Apple has come out with an iPod Nano that also records video, the obvious question is: is it as good, or better, than Pure Digital's Flip Mino, or Kodak's Zi8. Wonder no more: Macworld has done a head-to-head comparison – throwing in the Apple iPhone 3GS for good measure. The results speak for themselves.
(Macworld) | For further info: see here and here, and here

Love Art: National Gallery, London is a free iPhone/iPod touch app providing over 250 high-resolution, zoomable images of paintings and 200 mins of video and audio commentary and interviews. Includes access to a Google map of the gallery (provided Internet access) and a link to its website.
(Source: Macintouch) | Cost: Free | Requires: iPhone, iPod Touch | For further info...

Lest you think that The Library of Congress was just about books, it has begun releasing videos from its archives through its own YouTube channel, starting with 70 historical videos, inclulding the first ever moving image (a man sneezing), films from the Thomas Edison studio and industrial films from Westinghouse factories.
(Source: Wired) | Cost: Free | For further info...