What's Your Company's Wedge?

I watched an interesting talk yesterday by Garry Tan at TechCrunch Early Stage where I learned about your company's "wedge." The thin edge of the wedge is a small and specific problem/solution you're working on now. The thick side of the wedge is where you can grow into eventually. He gave the example of Airbnb. Airbnb started out at a thin wedge, where in order to host you needed an air bed and to provide breakfast to your guests. And now at the thicker side of the wedge they have all sorts of hosting experiences. For me, the thin edge of the wedge is private scratch notes. The thick edge is all of your notes/knowledge use cases. What's your wedge? What are other wedges you've seen?