Fiendish Minimal
Fiendish Minimal was designed out of my need for a multi-column, responsive, minimal theme for my car blog.
It's not much, but I've put a lot of love into it.
Features
Responsive design that degrades from three columns into two and finally a single column for mobile browsers (Looks nice however large your screen is)
Sticky header (It's sticky!)
Infinite scroll and cute custom loading gif (Pages are for geeks)
Reasonable customisation pre-filled with global appearance settings (Make it look the way you want - just don't make my theme look bad single tear)
Readable code and a Creative Commons license for the tinkerers (Like me)
Expand posts by tagging with x3 or x2 to triple or double their width on grid pages (Highlight important posts)
Unleash the 90s with options to colour up your posts according to the tags - set the tag you want in the theme options, and then simply apply the tag when you create the post. Pink, Blue, Green and Yellow (#ff3399, #3399ff, #33ff99 and #ffe199)
This isn't a paid theme or a team effort, so it's pretty simple, but at least you can find the customisation settings you want easily, and hopefully at ~52kB for my components, it will load up pretty quickly.
Contact me @ floatingdino.tumblr.com if you have any questions or suggestions
Enjoy!