For merchanting, it could be like having some kind of localized resources, which can be acquired in one area and taken to another area where it is lacking, and a profit can be made there. Also, it could be that the player has the ability to setup a store which stocks items of theirs, which other players can then buy from. It could possibly also be NPC vendors with semi-random buy/sell prices which fluctuate enough to potentially make money by buying low and selling high. If players have the ability to trade, I'm sure they'd figure some other stuff out.
Closely related to merchanting, especially the traveling kind, it'd be interesting if you could be a bandit, stealing someone else's things by killing them (or holding them hostage or something). Merchanting isn't as fun without some risk, and other players are unlikely to ever present adequate risk without it benefiting them. It might also be an idea to have actual stealing abilities, which can perhaps target currency or items, assuming they were skill-based or otherwise balanced to be somehow avoidable and to prevent unfair use.
I'd also like to see skills which you become more proficient with through use, although it'd make sense to impose some restrictions to stop senseless spamming (as an example, attack spells don't level up unless they land on an opponent).
And while I'm naming off random stuff, I'll throw on global quests and player-made quests. The global quests would be something everyone randomly gets at the same time, but only the person/group that accomplishes the randomized objective can get the reward. This would (should) be abusable in the sense that a single player could come in and finish off a "kill creature" objective with one hit after other players took the time to fight it, and receive the reward for themselves.
The player-made quests would just be some system in which a player can define/setup an objective of some kind, submit a reward, and then other players (and that player) could attempt to accomplish the goal set forth, receiving the reward immediately upon completion. This could potentially be combined with the global quest idea, allowing players to generate global quests as well. One use of this would be being able to place a bounty on someone else's head.
Oh yeah, and as an additional cool thing to see, player-made traps
Plus crafting, and enchanting (including cursing) objects.
Let me know how any of that sounds
Post has been edited 1 time(s), last time on Jul 13 2012, 10:19 pm by Azrael.