Expanding on Bitcoin
Here are some examples of new functionalities being built on top of the Bitcoin blockchain:
Colored Coins
Colored Coins work by tracking particular Bitcoins. These Bitcoins can then be used to represent assets other than their literal Bitcoin value. Colored coins can be used to represent stocks, bonds, smart properties, other currencies (such as dollars, pounds, yen, or euros etc.), and different tokens like access tokens. One use case that has been mentioned is a store using them as part of a "loyalty program".
Blockstream
enables bitcoins and other ledger assets to be transferred between multiple blockchains.
Counterparty
Counterparty uses the Bitcoin blockchain, along with its own currency (called XCP), to enable the execution of "smart contracts". It is a platform that others can build on to create applications based on these smart contracts. One notable example of this is the social network, "GetGems", which pays users for referring new users.