Communication services need interoperability to succeed - and Loopt is the first such service since SMS that is available across all major U.S. wireless carriers.

There's this famous observation that I totally believe: Great startup ideas are the ones that lie in the intersection of the Venn diagram of 'is a good idea' and 'looks like a bad idea.' So you want most people to think it's a bad idea and thus not compete with you until you get giant. But for it to secretly be good.

Never put your family, friends, or significant other low on your priority list. Prefer a handful of truly close friends to a hundred acquaintances.

Making money is often more fun than spending it, though I personally have never regretted money I've spent on friends, new experiences, saving time, travel, and causes I believe in.