Link: OpenBSD spamd
OpenBSD spamd - greylisting and beyond is a presentation by Bob Beck of the University of Alberta about the OpenBSD's spamd system, how spammers react to it and similar systems, how you can exploit this, and the University of Alberta's experiences with spamd, complete with interesting numbers. I'm sadly jealous, as local feelings insure that I'm not going to get to deploy this sort of technology any time soon.
(Also from Richard Johnson of river.com.)
Link: varnish, a HTTP accelerator
Varnish - the http accelerator [PDF] is the slides for a presentation about a HTTP accelerator for dynamic websites/CMS systems (its website is here). Slide three made me laugh out loud, and I have to say 'what he said'.
(From Richard Johnson of river.com.)