I always liked Gears of War's camera perspective because it balanced getting a good look at the character you are playing with being able to see the action. While playing around with locking the camera distance in Oblivion, I found that a similar perspective could be achieved in Oblivion. This mod locks the 3rd person camera into a view right behind the player. While you could achieve the same effect through using the scroll wheel in vanilla, I was always fiddling with the scroll wheel, so locking it people like me from messing up the nice perspective.
Granted, it's not perfect. Someone who specializes in marksman may find themselves switching to first person view because then they can actually see their target without the player's head blocking their aim. But it works well for combat, especially if you have a third person animation replacer like DMC Stylish or Seph's Dual Wield.
I included two versions. If you're crazy like me and would like to attempt archery in the 3rd person on a regular basis, you should probably use the Tight version so you are always facing the direction you'll be shotting. If you are not an archer, or just prefer the gentle lagging rotation of the vanilla 3rd person view use the Not Tight version.
If you wish to revert back to whatever camera you were using before, just disable this mod and it'll go back to normal.
Also, if you plan to play in 3rd person regularly, I'd recommend getting a 3rd person cross-hair mod.
I use the one by krytonix which can be found here: http://www.tesnexus.com/downloads/file.php?id=2706
I might work later on improving this and making it more "Over-the-Shoulder" instead of "HEY PLAYER! CAN YOU MOVE YOUR HEAD! I'M TRYING TO AIM HERE!" but I'm happy with what I've got now. It's perfect for what I wanted. Plus doing that would mess up 3rd person crosshairs... =P