Pronto is a very minimal grid style Masonry WordPress theme that I created and you can use absolutely for Free. It runs off the native Wordpress posts so you can create either a gallery or a unique blog. Enjoy!
License: FREE GPL
Theme Features:
*Masonry Powered Grid – items re-arrange depending on your window size
*Post-based theme – no custom post types, just use regular posts to create your structure
*Featured image support
*PrettyPhoto lightbox for single post featured images
*Notification bar area for putting important notices
*Custom logo upload field
*Flickr widget included
*Author pages
*Threaded comment support
*Works well with WordPress 3.3
*Free GPL theme
*Very clean and minimal design – easy to re-skin and customize