I've found horses/armor/name tags to in the member world.
Problem is worlds aren't created because people can't find things.
They get created out of a necessity for building space.
That basically leaves you with two options:
A) bug our good ole' admin nick about addin armor/name tags to the market (hes already considering armor, tho he doesn't wanna add name tags for some reason, there's already a couple threads about it)
Or
B) start building massive awesome builds all over member world until all the space is used up. (Should take about 6 months)
Good luck with which ever endeavor you choose to pursue.
P.S. option B would be way more badass