Development

BSD Sockets: A Quick And Dirty Primer
Crash course in programming BSD sockets
http://www.ugu.com/sui/ugu/show?I=help.doc.network.sockets&F=1111111111&G=Y

Building an OpenBSD port
Information on porting software to OpenBSD.
http://www.openbsd.org/porting.html

The Kame Project
Project to develop IPv6 and IPsec stack for use in BSD-based operating systems. Included in the OpenBSD sources since OpenBSD 2.7 Release.
http://www.kame.net/

OpenBSD - owc / odc
Mailing lists hosted by Squish.net that collate the OpenBSD source-changes and email summary reports daily or weekly.
http://www.squish.net/openbsd/

OpenBSD commit stats
Statistics on the number, type, and originator of commits to the OpenBSD CVS repository.
http://www.oxide.org/cvs/

OpenBSD kernel source tour
Hypertext markup of the OpenBSD 2.3 kernel sources.
http://tamacom.com/tour/kernel/openbsd/

Porting audio applications to OpenBSD
Reference information regarding porting audio software to OpenBSD.
http://www.openbsd.org/audio-port.html

Porting BSD UNIX to a New Platform
Paper discussing what is entailed in porting the BSD codebase to a new architecture.
http://tofu.alt.net/~lk/291.paper/291.paper.html

PPP userland tools
Latest docs and sources for userland PPP for OpenBSD.
http://www.awfulhak.org/ppp.html

strlcpy and strlcat--Consistent, Safe, String Copy and Concatenation
Whitepaper by OpenBSD developers Todd C. Miller and Theo de Raadt discussing secure programming functions for manipulating strings.
http://www.usenix.org/events/usenix99/millert.html

Unofficial OpenBSD pathces
List of unofficial OpenBSD pathces done by Sergey Smitienko.
http://www.comsys.com.ua/files/