lighttpd

In my job, I deal with a lot of tcp traffic, esp http, and ipv6.

For awhile I've been using both bozohttpd and Apache.
I used bozohttpd because it's simple, light weight, command line driven and easy to hack on. The big win for bozohttpd was the fact you could drop it into inetd and let inetd take care of the ipv6 compliance side. However, bozohttpd is lacking in several useful features and in many cases is missing some standards compliancy -- so in those cases I used Apache. Everyone here tests with Apache, but I absolutely despise Apache's convoluted "do everything" configuration and setup. It can take me hours to remember, research and setup even simple changes (esp if it requires a missing module!). Compiling Apache can be a royal PITA... Basically, it's too flexible.

Recently I've taken a liking to lighttpd. It's very fast, easily configurable, and restricted enough in it's feature set to allow easy module configuration. It only has one problem. You could use it for ipv6 and not ipv4 or vice versa. Common mistake really, people never take the time and effort to use sock storage structure and properly do a dual stack server, they try to 'hack' their ipv4 server into v6 with #ifdefs, etc. Bad bad bad. I digress.

Adjusting lighttpd to work on v4 and v6 in the same process was easy. Easy that is if you're using freebsd.

sysctl net.inet6.ip6.v6only=0

Then set up lighttpd to serve v6 addressing, and you're set. This basically enables v4 compat ipv6 addressing like ::ffff:172.16.17.1, so all their #ifdef'd ipv6 only code still chomps on the numbers just fine and listening on :: still gets you v4 traffic.