Uncharted 2 DLC wasn't justified whatsoever. It's hard enough as it is to get into a match, for crying out loud.

All the Pain unlocks..

I paid like 20 euros for chars, extra modes and so on, but then i found the Blu-Ray version included all of them.

The Borderlands extra missions... since they released another version with all of them!

that final fantasy tower defense game.

I don't buy much DLC but I bought two of the Duels of the Planeswalkers complete decks DLC today (I was curious of the game was still as bad as I remember it).  Even at 80 points a piece it was still a massive waste. 

If I had to pick one, gosh that's hard since they're both pretty worthless, but the white one I got was especially bad.

Borderlands Mad Moxxi's underdome riot. Man that dlc sucked compared to the rest. It was just way too boring even with 3 of your mates.

witch hunt for dragon age.  The DLC for that game just got worse and worse with each subsequent release with it culminating in the release of witch hunt.  Couple of fetch quests, generic characters, and stupid freaking story.  Should never have been made and they should have never charged me money for that crap.

FF:CC My Life as a King DLC

Mad moxxe colssium for borderlands.

Hmm,  probably bought more than 100 pieces of DLC...it is really hard to name one...I guess the one(s) from Ace Combat 6,  you could buy like 20-30 airplanes but had to buy them all at a time..