Profit models for open source, part 1 - Firefox

In my quest to find a profit model for Varnish Software we took a look at how other projects manage to generate revenue. My favorite was Firefox. Firefox is one of the most successful open source projects ever. It's has had a huge success, both in terms of marketshare and revenue generated. It has managed to get huge penetration in the main stream. An impressive feat.

Firefox is a reasonably new project, with its 1.0 release about six years ago. Due to almost perfect timing and really good quality it's adoption grew in a huge way.
Today Mozilla Foundation has revenues of about 100 million USD. So how does Firefox generate revenue? First and foremost its the little box in the upper right corner. It sends traffic to Google, then Google shows a few ads, sometimes people click the ads and then Mozilla Corporation gets a share of the revenue. Brilliant, isn't it?
Some of the most success open source projects make money with open source - not from open source.
Let me know if you have any suggestions. Input on how Varnish Software could generate revenue with its product is very welcome.