SerLooK is a KDE application for inspecting data going over serial lines. It can work as a binary terminal that sends and receives data through a defined port (Point to Point mode) and displays them on separate views. Each view can be configured to display data in hexadecimal, decimal, octal, binary, and raw ASCII. It is also possible to perform I/O through terminal emulation views and define a secondary port and monitor the traffic between two external hosts using a "Y" cable (Snooper mode).
SysopView shows information in a visually attractive way, like computers in movies do. The idea is that it can show information relevant to system administrators non-comprehensible for non-technical personnel, while still looking attractive even if you don't know what is shown. The current version can show nagios status data, webcam streams (mjpeg, jpeg, and video4Linux), and VNC, has a built-in terminal emulator in which regular text applications can be run, can sniff the network (including remotely) and dissect streams and show pictures which are sniffed, can show external bitmaps (from, for example, mrtg and rrdtool), and can scroll text (currently showing output of rssfeeds).
ipredirectd has functionality similar to netcat but with some extra features. Multiple clients and full logging of network traffic are supported. It can also manipulate incoming and outgoing text traffic. Manipulation is based on pattern files that support regular expressions. This feature is probably most useful with HTTP. The software is smart enough not to apply regular expressions on non-HTML data by reading the content-type header. One possible usage is redistribution of pre-authenticated Web pages in foreign domains by replicating authentication and session cookies.