dpkg-du is a script to produce a dump of the installed size of Debian packages in du format. This is to enable ease of reuse with pre-existing scripts administrators may have to deal with 'du' format lists. For example, dpkg-du|sort -n|tail -10 will show the 10 biggest packages on your system.
MAC vendor check is a script that gathers MAC addresses in a network and creates a list of the vendor of each device. It can be use to quickly check whether strange devices are present on the network, especially if there is no dedicated management software (like Cisco Works) in use on the network.