PuPiPo! - Short, sweet, and weird as shit. Not really a comedy, not really a drama, 4 minute episodes, interesting art style.
Kotoura-san - Same kinda deal. Heavier on the drama, but still a solid comedy with well-written characters. Suffers a bit in the early second half though.
Mikakunin de Shinkoukei - Great animation (motion wise, less so art wise), really strong comedy.
And nobody mentioned Hitsugi no Chaika so far (except tangentially above by MFauli)?