How about another new mine. A HUGE mine, such as moria mines from The Fellowship of the Ring. In it, there are many crystals to each room, where the gems from each crystal vary. Also, the shape of each crystal varies. One neat part about this, the value of each chrystal changes after each server reset, so that people will not know which rock gives the most payout.
Make it far underground, with large pitfalls. Noobies who fall from the steep ramps that lead down into the mines meet threir doom.
Also, theives can spawn near your location as you mine to give you more trouble (some ppl AFK mine). These theives will theif up to 50k in items and money, then #hide.
Im sorry eViL if im doing the easy part and leaving these up to you, I need to learn how to use worldcraft... Even the serious sam editor confuses me.