David Szetela offers an extensive tutorial on the essentials of crafting "killer" PPC ads, including everything from touting your competitive advantage (awards and accolades), using a decisive call to action, highlighting benefits as opposed to features, and even creating a sense of urgency. And he includes examples of each tactic.
He also explains the one and only goal of a PPC ad. "Let's agree on one thing: the objective of your ad," Szetela says. "Is it to sell your product? Get a sales lead? Nope. Your ad's objective is this, and only this: Get the click."