I miss using stoneform all the time even though I never had a clue what it did.
I miss hitting level 40, and being so excited because I bought my mount, and was finally able join an X-roads raid.
I remember meleeing with my hunter wielding Herod's axe to get the whirlwind proc.
I miss fiddling with all the random engineering crap I made while leveling it.
Also, when I made my first horde toon, a troll, and was level 7 or 8 heading to Orgrimmar. My jaw dropped when I saw the gates and my facial expression was pretty much this O_O