I saw a really cool custom forum that has a responsive design, and I like the grid design they have to display them:

One of the best features is when viewed from a phone, it aligns all those images into banner size items one on top of the other. It makes it very attractive for mobile users which account for 60% of my traffic.

Are there any tutorials, plugins or examples out there that could point me to the right direction?

[@netweb Keymaster 10 years, 11 months ago]

Is that a bbPress site?

There are some docs on the codex to get you started modifying your bbPress setup

Codex