My suggestions for Terraria are:

-When there are more than one enemy, say how many of a multiple enemy there is, and tell what enemies there are

-I also think that SlyFox's suggestion of a new boss, the Hydra is a good idea for the Ocean Biome.

-There should also be more monsters for the floating islands, like guardians, or in my mind: Griffins.

-There should also be and egyptian theme in the desert. the underground pyramids. There would be great rewards in it. You would have to dig down in the sand to find a pyramid, and they would have awesome rewards. One vanity item being the Pharoah's Burial Mask, or the a mummy popping out of a coffin occasionally.

-In the Ocean Biome, the Ruins, guarded by the Megalodon, the giant prehistoric shark.

-Also: I would like a Snow Biome, one of the monsters being an Evil Snowman, as funny as it sounds.

-What would be cool would be snowball fights as Blue mentioned.

-There would be icicles as arrows that you got off trees in the area. Also a freezer would be nice to make them. You wouldn't be able to use these in Hellworld, as they would melt.

-Also, bosses for the underground jungle, and Hellworld if you please. Maybe a silverback gorrila.

-One word- PETS!!!

-A way to make your own music for the night and day things. Maybe a Maestro NPC to make your own music.

-Mounts, if you please.

-A simpler way to set up a server for multiplayer.

-If since in 1.0.6 you downgraded the potions, why not a greater healing potion?

-What would be cool would be if you put a cape of flight on the floating islands, super rare, and you can fly forward, not just up with the rocket boots.