Okay, this Cheydinhal Petshop mod has weapon racks - what they are like exactly I don't know because I haven't been there yet although I do have it installed (busy doing other things right now) ... but you might want to check them out.
The petshop is in the same abandoned house of the DarkBrotherhood Questline, but it is refurbished into a petshop with the brotherhood hidden in the cellar.
Hope they are the kind of weapon racks you are seeking. If not, look into using the mod and finding the old scripting for the "weapon-rotate' and racks that stored weapons script from Morrowind and think about editing the scripts to fit your racks in Oblivon. All I can think of.
Download for Cheydinhal Petshop =
http://planetelderscrolls.gamespy.com/View....Detail&id=1142