Skills Permanently Above Maximum:

I don't know of any other places to increase your skills besides the ones that i'm about to list.

Once you have level 100 in any skill you may or may not be able to increase that skill with a skill book unless you have already used it.

Here is an example-In the Shivering Isles there is an argonian in a town called Bliss who you have to retrieve a cursed fork for. Anyways, after you give him the fork he gives you a choice of a skill upgrade. The choices are a 2 pt. upgrade on Blade, Alchemy, or Sneak. Since I had level 100 Blade I decided to experiment and I now have a permanent level 102 Blade plus my armor bonuses which ends up equalling level 134 Blade. It actually does more damage than level 100 Blade.