I came across oEmbed the other day, completely by accident. I've been working on a couple of projects in my free time and in a few of them I really wanted to be able to embed better information about a URL, if it existed. I'd been working up my own rough JSON schema that was in many ways similar to oEmbed.
Then I came across a tweet that mentioned embed.ly and oEmbed and embed.ly are the perfect solution. Instead of rolling my own service I'm integrating theirs.
At it's most basic it's a standard way of getting more than just a link you can embed in your site and provides a standard interface for doing it across the web.
If you're looking to embed things in your website, take a look. There are plugins available for wordpress and others as well as a jQuery plugin you can use pretty much anywhere.