1. Introduction
This post lists some resources on how to create smart contract from scratch. To browse online smart contracts, Etherscan and Etherchain are two good websites.
2. Programming Resources
There is an excellent tutorial about how to program smart contract using Solidity here Smart Contract.
3. Hello World with Geth
This page will help you build a Hello, World contract with the ethereum Geth. The code is taken here for future reference:
4. Mix IDE
Here is a post on how to program and debug with Mix IDE.