I found that Shutter and Shutter 2 (or reloaded) are both responsive.
Using Shutter Reloaded for the time being.
Shadowbox, Pirobox, NyroModal, Highslide & YUI all looked promising, but don’t come as a plugin, didn’t have time (or patience) to do the integration into WP myself.
Thanks again for the good work.
E.
