How can a transaction have more than one recipient address? I see a lot of transactions which have more than one recipient address.

Examples:


Transaction 1
Transaction 2


Edit #1:
I just saw a tag call multi-sig-transactions. It is obviously what I am asking for. 

I did not see in the clients before. How come that there are so many of them?

Edit #2:
After reading little bit about multi-sig-transactions I am not really sure that these transactions are these multi-sigs. This opinion is not based on real knowledge but just on such a great number of these transactions in every block.
Actually, most transactions you see will have two recipient addresses. One is for the actual transaction and the other one is change.


  When the output of a transaction is used as the input of another
  transaction, it must be spent in its entirety. Sometimes the coin
  value of the output is higher than what the user wishes to pay. In
  this case, the client generates a new Bitcoin address, and sends the
  difference back to this address. This is known as change.


But you can also add any number of recipients to a transaction so you'll find transactions with 20 or 50 receiving addresses too if you look around. In Bitcoin-Qt simply click "Add Recipient" on the "Send coins" tab.