Slof's Horses, Better Beasts, Dogs, Khajiit Retexture, Robe Trader, and Claws. Then there's Windsurfer's AliveWaters. Ugh. It's awful, but that's all I can think of for immersion mods. You really don't wanna play without Slof's horses though for sure. The black horses in vanilla Oblivion are PURPLE >.<