Recently found this nifty little web app, coment.me, that can be used between designers and developers.
This app takes a screenshot of a URL you give it and allows you to draw, add notes, and point arrows to things on the page.
This is especially useful when a designer has a vision for how a header navigation should look for instance, when communicating it to a developer. Rather than a designer taking a screenshot of a website and bringing it into Photoshop and attaching it as an image to an email.
Just provide the URL, mark up the screenshot, and share the URL via skype, messages, email, whatever you fancy.
I dig it!