Paul English is the co-founder of Kayak, the travel search engine. He relates how Kayak got traction, including an early deal with AOL and how they launched with 15K searches/day. Paul also gives advice on recruiting and explains how it impacts getting traction in a fundamental way.
This interview is ~30min. If you just want the audio, use the mp3 version. You can also get the video on your iPod/iPhone via iTunes.
For more interviews, visit the Traction Book site.