Responsive Gallery Grid is a WordPress plugin by Jules Colle that changes the native WordPress gallery to a gallery that nicely fits your images into a jigsaw-like grid. Much like the Google+ gallery.
Features include:
The gallery will fit in nicely in a responsive web design, as the grid is recalculated when scaling the window.
By default the images will pop out a whenever you move the cursor over them. The z-indexes are updating so that the pop-out images are always on top.
The animation speed, scaling, margins and max row height will be customized in the next version of Responsive Gallery Grid.
The plugin detects whether you are using a mobile device, and will not load the unnecessary pop-out JavaScript if you are viewing it on your phone or tablet.
Demo: http://bdwm.be/rgg/?page_id=2
Download: http://wordpress.org/extend/plugins/responsive-gallery-grid/