All these WordPress themes are free and use post thumbnails so little if any tweaking is needed.
Mh Magazine Lite
This is the free version of MH Magazine WordPress Theme, ideal to create amazing online magazines within a few minutes! Upgrade and support available.
A fully featured, responsive high resolution magazine & blog theme without compromise. Hueman presents what you love to write about in a visual & user-friendly way on all devices.
Fancier is a dark, responsive theme with 4 columns. Needs some tweaks but looks promising.
Point is a fluid responsive and multipurpose WP Theme. Through the advanced options panel, you can choose from multiple site layouts, backgrounds and color schemes, as well as control specific features of the theme.
A content-rich theme. Perfect for bloggers and magazine sites who wish to display extra content.
Gridster is a neat and tidy grid-based portfolio theme for photographers, artists and designers to show off their work.