Parallelism is a new responsive site template freebie for HTML5 UP. If you follow my work you might recognize it as a design I posted to dA a few months back but, due to time constraints on my part, didn't graduate past the mockup stage until recently. In any case, it's done, so here's how it works: simply drop in your thumbnails and the template will not only resize them to create nice, uniform, masonry-like rows, but also adjust the number of rows to fit the viewport size (bigger = more rows, smaller = fewer rows). Pretty cool eh? CCA licensed like all my other stuff, so demo/download it for yourself here.
PS: Demo images courtesy of the mind-blowingly talented Felicia Simion.