These are the dramas I've dropped:
Arakawa Under The Bridge: Usually I like surreal plots and weird characters, but this was waaay too much for me.
Binbo Danshi: seen 3 episodes. At the beginning I naively thought that a drama with 2 of my favourite actors could only be great, but soon enough I found out that this theory was far from truth.
Coffee Prince: the main actress was damn annoying.
RH Plus: Although this drama was badly written and the acting was awful, I actually found it entertaining for about 5 episodes. :D But now that I have >50 shows that I plan to watch, and several dramas on hold, I'm not sure that I'll watch this ever again.
Taisetsu na Koto wa Subete Kimi ga Oshiete Kureta: was very promising at the beginning. I had been looking forward to see Miura Haruma and Toda Erika act as teachers. And truth to be told, I got hooked on this show pretty easily. But problems arise after 4 episodes when the conflicts became meaningless. It would have been a great show if the writers ended it after 4 episodes. :/