Some of us have been playing The Elder Scrolls IV: Oblivion ever since it was released way back in 2006. Due especially to the countless mods available for the PC version of the game, it seems as if the adventure never ends.
Some Oblivion mods genuinely do enhance the game's overall experience, and Bethesda themselves have stated that they pay close attention to what the mod community produce. With that said, Egg Says Whut discuss eight small mods which greatly improved upon the vanilla Oblivion experience, and the basic ideas from which it is hoped Bethesda will incorporate into upcoming release, The Elder Scrolls V: Skyrim.
Nehrim is also a good mod but it felt more like an expansion than a mod to me.