Pnscan is a multi threaded port scanner that can scan a large network very quickly. If does not have all the features that nmap have but is much faster.

psk31lx is a simple text-based terminal program with a built-in phase scope and spectrum analyzer to aid in signal tuning. It uses a sound card to receive and transmit PSK31 tone.

tetradraw is an easy to use drawing utility that gives you an ease access to the high characters like smileys, card signs and the well known single and double frame line characters but much more. Also the changing of foreground and background colors is not hard to do.

pflogsumm is designed to provide an over-view of postfix activity, with just enough detail to give the administrator a "heads up" for potential trouble spots.

ParaView is an open-source, multi-platform application designed to visualize data sets of size varying from small to very large. The goals of the ParaView project include the following:

Duc maintains a database of accumulated sizes of directories of the file system, and allows you to query this database with some tools, or create fancy graphs showing you where your bytes are.