Remote collaboration, especially with design isn't easy. Has similarities to Skitch (http://evernote.com/skitch/) and ConceptShare (http://www.conceptshare.com/). You should also keep an eye on what @tommoor, @ericbieller, and @mattboyd are doing with Sqwiggle (http://sqwiggle.com).

Needed it when I wanted to share feedback here on Product Hunt. Emails and screenshots don't cut it.