cweb.tgz: CWEB(3.64) for Plan 9. You need touch common.c ctangle.c before compile use mk.

mmix-20060918.tgz: MMIXware(20060918) for Plan 9. You need (install) CWEB(3.64).

figlet222.tgz: FIGlet (Frank, Ian & Glenn's Letters) release 2.2.2 for Plan 9.

9intro.tgz: examples of "Introduction to Operating System Abstractions using Plan 9 from Bell Labs", 
see http://plan9.escet.urjc.es/who/nemo/9.intro.pdf