You can hang anything you want, but small things are best of course. Quick to make and great for the cubical.

I hang my GEEK key-chain on it. Geek key-chain from http://www.thingiverse.com/thing:4193

You can hang your ring, desk key, etc....

Print both parts, and insert arm into base. Little if any shaving of the base hole was required.

After putting the arm in I put a dab of Acetone in the hole on the bottom just to make glue it in place.