Picture it with me: an MMO based in the Italian Renaissance. Races could correspond to the various city-states of Italy, or to foreign nations, perhaps. Play as:

• Merchants (sea voyages out of Venice, perhaps?)
• Unscrupulous churchmen
• Stiletto-armed assassins
• Scheming Medicis
• Your typical painter-sculptor-scientist-architect renaissance genius (should be an epic roll, this!)

Imagine riding into battle atop some Leonardo-designed war machine! Fencing with rapiers! Imagine going on quests:

• Steal the head of John the Baptist for the glory of Florence
• Dissect executed prisoners to level up in Anatomy
• Bring back exotic goods from around the Mediterranean
• Earn yourself an equestrian statue in your city-state's palazzo with military exploits

There's something very appealing about this, at least to me. It would be just the thing to finally get me to play an MMO.