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Coin

contract Coin {
    // The keyword "public" makes those variables
    // readable from outside.
    // declares a state variable of type address that
    // is publicly accessible,
    // does not allow any arithmetic operations. It is 
    // suitable for storing addresses of contracts or
    // keypairs belonging to external persons
    address public minter;
    mapping (address => uint) public balances;

    // Events allow light clients to react on
    // changes efficiently.
    event Sent(address from, address to, uint amount);

    // This is the constructor whose code is
    // run only when the contract is created.
    function Coin() {
        minter = msg.sender;
    }

    function mint(address receiver, uint amount) {
        if (msg.sender != minter) return;
        balances[receiver] += amount;
    }

    function send(address receiver, uint amount) {
        if (balances[msg.sender] < amount) return;
        balances[msg.sender] -= amount;
        balances[receiver] += amount;
        Sent(msg.sender, receiver, amount);
    }
}

Simple Storage

/**
 * collection of code (its functions) and data (its state)
 * that resides at a specific address on the Ethereum blockchain. 
 * think of it as a single slot in a database that can be
 * queried and altered by calling functions of the code that 
 * manages the database 
 * **/
contract SimpleStorage {
    //declares a state variable called storedData of type 
    //uint (unsigned integer of 256 bits)
    
    uint storedData;

    function set(uint x) {
        storedData = x;
    }

    function get() constant returns (uint retVal) {
        return storedData;
    }
}