Giving your forum an entirely new look and feel is easy — just download one of these great themes! There are even themes for the admin control panel.
Projects in Responsive
Elusive is a clean and elegant Flat MyBB theme which can be used by all sort of community users. Elusive is a mobile-friendly, fully responsive theme for MyBB 1.8.11, optimised for performance.
Free Responsive MyBB Theme - NetPen
A mobile friendly, responsive theme for MyBB.