Code Geass and Death Note definitely.
I'd also say Eden of the East had this effect.
there have been some others that hooked me initially but didn't keep me hooked all the way through-Black Cat is one of these. I did finish it but considering how amazingly awesome the first few episodes were, the rest of the series was relatively underwhelming. Shangri-La was another one that had me hooked at the beginning and then went so far downhill a few episodes later that I doubt I will even finish it .
The most recent one would be Minami-ke, and i'm not sure why. Well, actually, I am. It had to be it's awesome cast and well done comedic timing. I blew through that series in under six days, and I still want more.