Just a few things which I think would be cool to fix up.
-A "buy back" system like they have in WoW, in case your an idiot like me and sell Ess's RoE's

. I'll repay you one day buddy!!
-A way to "highlight" multiple things in your inventory, so you can drag/drop onto the vendor. Definitely a huge timesaver when it comes to ringshopping.
-On UN they have something so that you can save your complete outfit. It would be cool if you could switch from a "PK set" to a "mage set" or "fashion set" within just a click of a button. Or even creating a /equip function so that you can bind all items to 1 hotkey.
-As mentioned in a previous post, making "god switching" not as easy as just praying on the altar, accidents do happen.. durrr D:
-More zombie locations, or possibly making a zombie location where it's like "the crypt" and you aren't bothered by lower leveled leechers

.