Brainstorming on whats needed in a co-op mod and what do we need to get rid of in order to make it work.

To get rid of:
-Pausing
-Main Quest line and make a faction instead
-Fast travel
-Adjusting of time so shops open

What we need:
+A server to run the world
+Database for characters
+A better GUI to support 0-9 and shift,alt modifier to skills
+A max level of xx, max perk system
+A pvp On / off - to test combatskills
+A tradewindow but until that works, dropping [censored] in the gameworld will suffice.
+Better housing, perhaps even build your own.
+A way to release corpse apon death after xx minutes or be able to be reviwed by a friend, sometype of graveyard system.

You may want to search out the words co-op and multiplayer on the Oblivion and Fallout3 mods forums.

There have been a few attempts at what I would call false advertising in this department that have been met with not such great results.