Every six months, around May 1st and Nov 1st, OpenBSD makes an official software release. To accompany this free software released on the internet, we make artwork and music. This artwork emblazoned CDs and posters up until version 6.0, after which we stopped producing product and only release software on the internet.
Past releases also had shirts printed along with them.
OpenBSD developers receive exclusive t-shirts with additional artwork when they attend hackathons.
5.2 - 6.0
4.1 - 5.1
3.0 - 4.0