Code Geass. Right after Suzaku betrayed Lelouch.

Naruto Shippuden

There doesn't seem to be an end in sight. Sure, Naruto tries to convince Sasuke to see the "error of his ways". But to what end would he go?

I can't think of anything that I've dropped in the middle because I just couldn't stand it any more. There are shows that I've watched a couple episodes of and just not found interesting enough to finish, but the names of shows like that don't usually stick with me. I did get bored with the Bleach anime; I prefer it in manga form.

I dropped Lucky Star after 3 episodes

Bleach (got boring after 200 some episodes)
Black Lagoon
Fruits Basket
Soul Eater (might pick it up again)

I've never dropped an anime before. I just take them for what they are.

Phi Brain

shuffle is the main one for me, it literally pissed me off haha, the ending really bothered me to the point when I see it I cringe

But at the most part I finish and take most animes for what they are story wise

Eiken, i dropped it after the first 3 minutes, thats my record

I dropped Phi-Brain at like episode 19, which got pretty far, one of the few times i waited so long

Generally I have dropped tons of series at 1 episode that i cant remember, and a few recently at like 2/3 depending

Dropped -
Naruto Shippuden
Bleach
Phi Brain season two
Mysterious Girlfriend X
Baccano
Night Raid 1931
Accel World
Agent Aika
DearS
Gantz
El Cazador de la Bruja
GetBackers
Heroic Age
Gurren Lagann
Hiiro no Kakera
HunterxHunter (the older version)
Linebarrels of Iron
Needless
Now and Then, Here and There
Persona 4 the Animation
*special note* GunXSword - I actually tried to watch this twice. Both times I could not make it through the first episode.

Usually, I either give a show three to six episodes (depending on how long it is). In order to see if it picks up or the story goes downhill, etc. But sometimes I'm completely turned off while watching the very first/pilot episode. As was the case with these shows:
Black Cat
Blassireiter
Golden Boy
Elfen Lied
Love Hina
Guilty Crown
Sket Dance
Steins;Gate

Anime that was a complete waste of time:
Maburaho - harem anime, which I find detestable. I made it through half the episodes though, so I give myself credit for that.
Speed Grapher - yuck, just yuck. This show tries to be mature in content, but cannot pull it off in an adult manner. More like a teenager talking about something they don't understand. Made it through half the episodes.
X - Yaoi thinly disguised as "end of the world" greek tragedy. Not my cup of tea.
Dance in the Vampire Bund - I could on about this one, suffice to say it was in poor taste.
Peach Girl - Normally shoujo appeals to me, but even this was too much. I wanted to rip off Sai's head, and pound some sense into the heroine (who's name I've completely forgotten). Very frustrating, and I didn't care for the ending.

Guilty crown was awesome, sure the first episode was weird but it gets better...

well I dont remember any of the anime I dropped. fate stay night wasn't a complete waist of time but the game would probably be better if I knew where to get it.

Unlike a lot of people here I havent dropped bleach or naruto. (but I did skip large sections of them.)

I have grown out of pokemon and digimon.

Claymore. That kid's voice murdered it for me. Not to mention it was so cheezy I'm pretty sure it gave me high cholesterol. (lasted 2 episodes)

I actually just got into the 3 or 4 episode of Heroman when I stopped. There were a lot of things I HATED about that anime. 1. The main character is a wuss and a hypocrite 2. The bully of the show is one of the most stupidest anime character I have ever seen!! and 3. THEY NEVER EXPLAINED IMPORTANT DETAILS ABOUT THE CHARACTERS!!!!

Here's the show if you want to see it (don't ask me why I put this here, but I did and here it is):
http://www.crunchyroll.com/heroman

Horizon in the Middle of Nowhere
One Piece
Gintama
Beelzebub

Lucky Star is difficult for me to watch, but I hate to drop anime after I start. It's supposed to be funny, but I rarely laugh. It's so painful to watch.