How to use web app to share content in mobile?

I couldn't find anything on this. I read everything about protocol/content handlers but didn't seem to solve my problem at all.

I'm trying to find a way to allow an Android user (for example) to share content using a web application.

Examples:

1) Viewing a Youtube video in the native app. User selects 'share' and a bunch of icons appear. I want my web app to be there, so when user selects its icon, a URL is opened in the browser with a magic parameter passing the video URL so I can handle that. 2) Well, you get the idea now :)

Any ideas?

Thanks.