Coda Notes, a Safari Extension

Coda Notes, a Safari Extension:

It's not available to the public yet, but the idea seems promising:

When you install Coda Notes, you'll get a new button in your toolbar. Click it to see all our annotation tools, built right into Safari. Draw some notes on your favorite website. Communicate changes, ideas, concepts, or problems. Then, when you're done, hit the Send Notes button and the whole page flips over as a postcard.

/via Daring Fireball