GitHub's new image compare mode[1][2] would work really well for designers*

[1] Blog Post: https://github.com/blog/817-behold-image-view-modes

[2] Demo: https://github.com/cameronmcefee/Image-Diff-View-Modes/commi...

Coupled with Kaleidascope on the desktop: http://www.kaleidoscopeapp.com/

I think the problem is introducing the IDEA of version control to designers. Once they grok the idea, they usually like it. But with the exception of web designers, most designers aren't introduced to the concept.

*I was a designer before I was a developer