Concept art released by Bethesda. This stuff is just great! There had been no updates in a long time, but now, there's plenty, and hopefully plenty more to come :) To download, simply click on the respective thumbnail.

Concept Art #15	A female warrior in Daedric armor, and a Dremora for comparisson.
Concept Art #14	Dark Brotherhood armour - gotta wonder if all those dangly bits don't make a lot of noise :o
Concept Art #13	The Mithril armor we have already seen, but in a much nicer presentation.
Concept Art #12	Concepts of Minotaur, Scampr and Clannfear. Is that a typo or is a Scampr something new?
Concept Art #11	Concepts of two old friends: Spriggan and Imp.
Concept Art #10	Concept of Troll and Dreugh - so that's what the thing in the trailer was, a Dreugh!
Concept Art #09	Targets and Dummies for fighting practice.
Concept Art #08	Concept drawings of an Elven Long Sword, Elven Long Bow, hilt of the sword and a quiver with arrows.
Concept Art #07	A picture labelled 'Arena Clutter' with various items you'd find in the fighting arena.
Concept Art #06	This drawing shows the layout of a city called Leyawiin which seems to sit on top of a river.
Concept Art #05	Plants called Blood Grass, Spiddal and Harrada - from the looks of those, these are native somewhere in Oblivion.
Concept Art #04	A concept drawing of a Fighter's Guild building.
Concept Art #03	A town guard with a tree logo on his cuirass! You will note the name "Chorrol" here. This was the first mention of this town.
Concept Art #02	A woman showing off a very nice Mithril chain cuirass. Here's hoping the NPCs in Oblivion will be as good-looking as this one!
Concept Art #01	A man wearing a Mithril helmet.