Haunt_House recently posted a very interesting question. It is set up similair to a code golf question, except for 3D models, as you might've guessed. He posted the desired outcome (a simple arrow), had some guidelines and looked for a solution that requires the least amount of clicks to achieve the goal.
I think this would be a pretty nice idea for a competitive style Q&A site like code golf, with a focus on any 3D modelling software, not just Blender. I actually already created a proposal on Area 51 in case anyone is interested.
If the new site doesn't come to fruition, having a "Challenge" tag for these kinds of questions would be a nice alternative, even if it would be focused on Blender only.
Side note: If the new site actually does become a reality, we could use this new challenge tag to migrate the questions over to the new site, if that's possible and wanted by the community.