What is an elevator 'sales pitch'? In short, imagine you're riding in an elevator with another person; possible customer, investor, media person etc. and you have only that amount of time it takes for you to get in, push the button, and ride. 30 seconds or less. What would you say in such a short period of time to get your sales message across.
Think in terms of writing a headline. That's because that'll be all the time you hve.