Pre-release Olaf could kill himself with E by taking damage increase masteries.

TF's gate use to be a regular ability


lol

heimer could damage towers with his E

Cleanse used to make you immune to CC for 2-3 seconds, (It was a fun Kat patch)

when someone died by non champs it said "humiliation"

Lets see...

Ryze's E was his ult and would one shot people at 6. Ryze's current E was a toggle that took 10/20/30/40/50% of his AP and added it to his AD, also gave him flat Mana as a passive.
Ezreal's W healed Allied units and his ult was 50% wider.
Corki was built AP because his rockets had decent AP ratios.
TF's Wild Cards had literally a 2000 range or something crazy
Flash range was 800
AD carries middle, kill lane bots, top was whatever
All the extra bushes in the jungle and around Dragon/Baron
Every champion OP
Phantom dancers had dodge- 100% dodge Sion

Beta gameplay videos for you youngins:
http://www.youtube.com/watch?v=JsALFGqpnys
http://www.youtube.com/watch?v=72XjiRRxx_M

also jax dodged towers and the stat was granted by PD
jax example

Ezreal was orginially released as a support where both his W and R healed allies it passed through.
Phantom Dancers used to have dodge.
Rally used to heal all allies nearby for the duration of the rally.

Eh, all I really know is OP purple caster minion. I played LoL when it first came out, but gave up when I couldn't grasp the MOBA genre.

Also, sliding Ezreal was funny, but that's not too old.

AD Katarina
Shen was THE best duelist in the game, being able to 1v2 effectively
Funfire garen
Pentakill Xin zhao (release)
Overpowered stealth. Eve was a common ban, then eve got pulverized and twitch nerfed.
When I started, I had a 1/25 chance to see a beta rammus player with a King Rammus skin.