Firestarter is a firewall tool for Linux, and uses GNOME. You can use the wizard to create a basic firewall, then streamline it further using the dynamic rules. You can open and close ports with a few clicks, or stealth your services giving access only to a select few. It features a real-time hit monitor which you can watch as attackers probe your machine for open ports.
The Bubbling Load Monitor (or "Bubblemon" for short) is a system load monitor for the GNOME panel. It looks like a vial containing water. The water level indicates how much (electronic) memory is in use. The color of the liquid indicates how much swap space is used. The amount of bubbles reflects the system CPU load. A message in a bottle indicates there is unread mail. A reed-like graph shows I/O load. On multi-core systems the CPU with the highest load will bubble in the middle, and the others on the sides, so it's possible to see how well load gets distributed between CPUs.
Cheops-ng is a network management tool for mapping and monitoring your network. It has host/network discovery functionality and OS detection, and does a port scan of each computer to tell what services are running. It can probe FTP, HTTP, ssh, email (port 25), news, IMAP, and VNC to see what version and type of server is running on those ports.
Akeni LAN messenger is a cross-platform instant messenger client. It is a P2P program that works on your LAN without the need of an Internet connection or a dedicated server. The client has an user interface similar to AIM, ICQ, or MSN Messenger. It supports all the standard IM features such as chat, group conference, presence management, file transfer, and emergency alert/notification. Extra features include contact management and optional tabbed chat sessions.
Akeni Instant Messaging Server Pro is a client/server instant messaging platform that allows companies to host their own secured private IM system. The client has an user interface similar to AIM, ICQ, or MSN Messenger. It supports all the standard IM features such as chat, group conference, presence management, file transfer, offline messages, and emergency alert/notification. Extra features include contact management and optional tabbed chat sessions. The server has advanced administration tools for managing user accounts, client-side logging capabilities, and peer-to-peer file transfers. It can be set up on a private network without connecting to the Internet, and can easily be set up for use inside and outside of the company firewall.
GWCC allows users to execute network utilities (ping, nslookup, traceroute), workstation commands (netstat, df, lpr), and do cool things like process grep from a single tabbed window. Command flags are highly configurable, results windows are savable and printable, and there is a System Stats tab showing you process info, current users, Apache server status, Samba status, and more.