We actually tried to invest in Twitter in April 2007, right when it launched. At the time, the company was wary of having a classic, tier-one traditional venture firm involved.
In open source, you really have to be near the watershed to have an impact on the source code. Customers want to be near the key contributors to the code, not a level removed.
We approached Yahoo and Jerry Yang and said that Hadoop is going to continue to be popular, and as it does, more and more of your team is going to get poached by other companies and come under pressure to leave. This way, you can control your own fate and destiny.
My biggest mentor has been the Benchmark partnership. We have six partners and a flat structure, and everyone is paid the exact same paycheck. It's a team model versus an individual model.
In open-source in general, the power lies in connecting the author of the software directly to users, eliminating the middleman.
The one I have the most angst towards would be YouTube. We had an opportunity to invest, and I just got nervous about the media industry's response to the unlicensed content on the site.