This is just a hodge-podge of interesting links to other places.

http://tools.ietf.org/html/draft-ietf-tcpm-newcwv-00
  Possibly a better solution to the TCP_IGNOREIDLE hack.

http://www.stuartcheshire.org/papers/NagleDelayedAck/
  Nagle and delayed ACKs

http://lists.freebsd.org/pipermail/freebsd-toolchain/2012-May/000411.html
  kib's@ alternate pstack(1)

http://people.freebsd.org/~pho/stress/issues/
  Summary of open issues in pho@'s stress2 suite