TrinityOS is a step-by-step, example-driven HOWTO on building a very functional Linux box with strong security in mind. TrinityOS is well known for its strong packet firewall ruleset, Chrooted and Split DNS (v9 and v8), secured Sendmail (8.x), Linux PPTP, Serial consoles and Reverse TELNET, DHCPd, SSHd, UPSes, system performance tuning, the automated TrinityOS-Security implementation scripts, and much more.
DataReel is a free, cross-platform database and communications toolkit. It can be used to rapidly develop and deploy multi-threaded database and communications applications. The DataReel toolkit is composed of a modular C++ library designed to build cross-platform infrastructures for end-user applications, embedded systems, and reusable libraries. DataReel's unique modular design simplifies adaptation, allowing you to determine the level of complexity. DataReel makes Internet connectivity and database programming easy.
vt52vnc is a VNC viewer which can be used on prehistoric green monochromatic terminals called vdt52s, which are capable of vector graphics. It is functional and nicely displays X on the terminal, but without the routines for dithering, compression, and password support. Its architecture provides a framework to add those features if needed.
Spinner is useful for keeping telnet and ssh links from dropping due to inactivity. Many firewalls and some ISPs drop connections when they are perceived as idle. By having spinner running, the server is constantly sent a tiny amount of data over the link, preserving the connection. Spinner thus acts as a keep-alive. It displays a little "spinning" ASCII character in the top left corner of your terminal. It supports any terminal capable of handling VT100-style escape codes. Spinner can also function transparently by only sending null characters to the terminal. In this mode Spinner supports any terminal. It also has a mode called "Ghost in the Machine" in which you can use Spinner to write the spinner character to any TTY, not just your own.
ThePacketMaster Linux Security Server is a CD-based security auditing tool that boots and runs penetration testing and forensic analysis tools. It is handy for security auditors. Some tools included are nessus, ethereal, The Coroner's Toolkit, chntpw, and minicom. It includes modules for any Linux 2.4.20 SCSI driver.