Mike Santullo and Larry Drebes are two of my favorite entrepreneurs ever. Every time I came to a board meeting, Mike and Larry would have a new software product or feature to demo. The energy in their company was palpable. They cold-called me on a Monday, we met that week, and had a term sheet the following Thursday. I felt like I needed to move as fast as they did. Four11 started as a lookup service for business websites. Then they met the Hotmail founders at a DFJ Schmoozefest and learned about web-based email and viral marketing. So they decided to do it themselves. They launched RocketMail. Sold it to Yahoo. The product is now called Yahoo Mail. It has 200+ million users today. The lesson is obvious. Speed matters. Energy matters.