Markup - Draw on any webpage and share with others

Markup is a beta service that allows you to draw on any webpage using simple tools.

You add their bookmarklet to your bookmark bar and then when you find a website you want to mark up, just click on the bookmarklet. No download needed. There is even an extension for Chrome.

You can use the cursor to draw lines and curves and even add text. There is an arrow, curve, circle, and square tool. You can also choose your colors. Make your markups and then publish and share them with others. People can then respond to your markup.

This is a great tool for teachers who want to share annotated web pages with their students, or even just to make notes so that when you look at the web page again later, you remember why you saved it.

Here's a markup I did on Tech&Learning's website: http://markup.io/v/4ysj130tdn8c

and here's a screen shot of it for you:
 (I circled the Techforum link at top, put an arrow with a label on the blog section, and put a box around the "follow us" menu.