xkey.c Attach to any X server you have perms to and watch the user's keyboard. http://firewall.com/software/xkey.c
ypsnarf.c Exercise security holes in YP / NIS. http://firewall.com/software/ypsnarf.c
YPX YP/NIS is a horrible example of "security through obscurity." YPX attempts to guess NIS domain names, which is all that's needed to extract passwd maps from the NIS server. If you already know the domain name, ypx will extract the maps directly, without configuring a host to live in the target NIS domain. (GZip'd Bourne Shell Archive) http://firewall.com/software/ypx.sh.gz