Here is a nice collection of early-stage startup pitch decks that managed to raise money successfully.

There are some common concepts in all of them:

• Most importantly, they are actually great ideas. LinkedIn, YouTube, AirBNB now look like totally obvious concepts, but back when they started out they were not.
• They explain clearly what the company/product actually does, often via a demo of screen shots. Many startups omit this important part of your pitch (surprisingly).
• Often, there is a very powerful traction slide inside. If you have grown your business from nothing to millions of dollars in 6 months, investors will pay attention, and forgive you if the rest of the slides in the pitch deck are not that good.
• All these decks are email friendly, you get the idea without the need for a presenter to explain it to you. (That is now actually the main type of presentation I design for my clients)