For example, I remember one where you can write notes in-game, and they became pieces of paper that you can read. But for the life of me I can't remember what it's called, so search engines can't help me.
Edit: Another one I wish I could find: what it does, is it trains up your magic skills depending on how many magicka points it costs to cast it, so you aren't just casting 1 mp spells over and over to train up.
