Feature Request: Choose different ads for mobile/tablet

I love in-post ads. However, on a responsive theme, a standard ad size that looks great on the desktop just won't work for mobile.

I think it would be really useful if the plugin allowed us to appoint different ads for different browser widths.

And I guess it shouldn't be too hard to implement, I 've seen other ad plugins, such as GARD (http://wordpress.org/plugins/google-adsense-for-responsive-design-gard/), take into consideration the browser size.

Thank you

Angelos Kyritsis