On IBM's developerWorks there's a recent article from Vikram Vaswani about using the oEmbed tool to pull content into your site from sources like YouTube, Twitter and Facebook.

If you have your photos in Flickr, your videos in YouTube, and your TV shows in Hulu, how do you bring them all into your blog posts on Blogger? Of course, you can do this by hyperlinking to the appropriate content, but wouldn't it be nicer if you could just embed them into your post at the appropriate place? Enter oEmbed.

He gives examples showing how to pull in content from a few different places - a video from YouTube, one from Revision3 and an image from deviantART. He also talks about using the oohEmbed service to access additional content on things like Wikipedia, Slideshare and Amazon. There's also a bit at the end looking at an alternative PHP library that could be used to do similar things, php-oembed.