[No1]

For the tl;dr people:

On the nginx side, author discusses tweaking sysctl.conf, cutting down the number of sockets stuck in TIME_WAIT, some other tweaks for performance resulting in a 90% reduction in occupied sockets. On the node.js side, author uses the cluster module to fully utilize available CPU cores, arriving at N-1 for the magic number of node processes to spawn, where N is the # of CPU cores.

Definitely suggested reading for anyone running Nginx + Node.js