Disruptive builds posted a shader settings for Minecraft video that makes look even better. If you are not using shaders yet, you should check them out.
The Cliffs and Caves update to Minecraft has really upped my dread level when I stumble into huge caverns. Not being able to see what lurks in the dark above or below me and the worry that I can be bumped off a ledge and fall to my doom adds a whole new level of stress. Not to mention the new baddie, the Warden in the Ancient City. I guess one good thing is the Warden is the only thing living in the city that can attack me but man, is it creepy.