A slashdot post about writing high-availability services provided a fair few links to interesting stuff about writing high-load socket applications.
High Performance Server Architecture - from pla.typ.us
The C10K problem - from kegel.com
Joe’s spitting in the sawdust Erlang tutorials - sics.se/~joe/
Linux scalability: Accept() scalability on Linux - www.citi.umich.edu
I don’t have time to read it all. One day.