nginx [engine x] is a HTTP and reverse proxy server, as well as a mail proxy server written by Igor Sysoev. It has been running for more than five years on many heavily loaded Russian sites including Rambler (RamblerMedia.com). According to Netcraft nginx served or proxied 4.24% busiest sites in January 2010. Here are some of success stories: FastMail.FM, WordPress.com.
In a comment an an earlier blog post, I was asked about users and the effect of different kinds of standards on users — I had talked about the effect of standards on implementors but not about end users. The commenter made some claims about what end users wanted, with reference (presumably) to users of browsers.
This is hard, so I might take a couple of whacks at it, but here's one pass….