Notable is a great collaboration tool which allows you to quickly get feedback on design, content, and code on a website project. Reviewers can capture a part of your page screen (design elements, code, etc.) and add comments and critique. Sign up for a free service or opt for a paid account. As a registered user, you will be able to quickly capture your screen using a Firefox plugin or an iPhone app and upload the images into your project's workspace where people can leave comments.

[via TechCrunch]