Thanks to the magic of technology, you can get mods for Skyrim on consoles now too. Mods are made by dedicated fans and range from little bug fixes and UI improvements to full-scale game system overhauls and DLC-sized quests, one is even due to become a full game.
One thing that keeps the game alive is mods. It's been released more times than anyone cares to remember, and is on about as many platforms as Doom.