The Toby intrusion detection system is a fairly complete reimplementation of tripwire-1.3 (ASR) into Perl. It mainains a database of file properties to detect alterations to those properties. It supports MD5 and SHA-1 checksums of the file contents. It features a configuration file which is actually a Perl script, with the attendant power, flexibility, and difficulty.
Hotspot Service retrieves billing information about wireless ISP hotspots. It uses a SOAP client to retrieve several types of information, including the current connections, transactions, gateways, and accounts, and whether the gateway is online. It can be used to create new accounts.
Sound of Traffic is an application that converts TCP/IP header information into MIDI notes via the Java Synthesizer. Its purpose is to listen in on network traffic in ordered time via a tempo rather than in real-time, which could be more chaotic. In this sense it becomes closer to music then noise.
Tweeter is another command line script that can update your Twitter status from the command line. It also uses the SSL link to protect your username and password. Tweeter can only post a new status; it cannot follow anyhone, send direct messages, or anything else. The username and password are not stored on the file system, so you can post to different accounts with ease. It should also work on older machines.
Xlogmaster allows comfortable and fast control of all the important system logfiles and devices that are readable via cat (/proc/XYZ for instance). Filters allow to raise/lower/hide lines. Due to usage of the GTK+ toolkit and full runtime configurability the user can modify the appearance of the xlogmaster to whatever fits his desktop best.