Trying to figure out what all the permanent buffs are that you can acquire over the course of the game, that don't involve equipment and aren't part of your starting character selection.

For example, Agent of Mara gives you +15% magic resistance, Agent of Dibella gives you bonus damage against the opposite gender, so forth. Ancient Knowledge gives you +15% smithing skill and a +25% armor bonus. What others are there?

http://www.uesp.net/wiki/Skyrim:Powers#Abilities

Well if you become a Werewolf you get 100% resist disiese. And if you contract vampirism you get 100% resist poision.