Slime Block

The Slime Block is an upcoming, transparent block that resembles a slime. It causes the player to bounce at various heights, depending on the length of the fall. The block is expected to be introduced in the Minecraft 1.8 version for PC. Such blocks are now able to be implemented due to a new rendering system. Slime blocks also causes players to move slower while walking on it. Both players and mobs who'd fall onto this block would take no fall damage.

As a crafting ingredient
A Slime Block can be crafted back into 9 Slimeballs, making it useful as a storage block.