Social sites like Twitter and Facebook have made it easy for you to quickly share news articles, blog posts, etc. around but wouldn’t it be nice if you could also add some of your own commentary to the page before sharing it with the world?

Well, there’s a new and interesting web app called markup.io that can help you here. It instantly turns any web page into a virtual whiteboard where you can add text, draw shapes, arrows or even do some freehand drawings. Here’s a quick demo:

Related: More tools for annotating web pages.

While you are on a site, hit the markup.io button on your browser bookmarks toolbar and it will float a set of drawing tools one that page. You can scribble over the page now and when you hit publish, all your drawings and annotations are saved to a unique URL that you can now pass along in your social circle.

If you make a mistake, you can use the usual keyboard shortcuts – ctrl+z will undo your previous action while the backspace key will remove the element from the page.

Markup.io is available in the form of a bookmarklet so there’s no need to download or install anything and it’s compatible with all browsers except for IE 6 (which you shouldn’t be using anyway). Thanks Richard.

Also see: Collection of useful Bookmarklets