GARP (Gnome ARP) is an ARP monitoring program written on Gnome with the GTK toolkit and Ruby. It takes ARP tables and some system variables via SNMP and ARP protocols and determines whether any machines have changed their IP address. It is useful for detecting new machines on the network and detecting which machine have changed addresses. It is intended especially for network admins.
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.
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.
Gnetload is a GNOME applet showing the network load of a specified network interface in a histogram. It is highly configurable; configuration options include different colors for incoming and outgoing traffic, fixed or dynamic histogram scaling, and textual representation of the current network load.
Computer Temperature Monitor is a little applet for the GNOME desktop that shows the temperature of your computer CPU and disks on screen. It also allows you to log temperatures to a file. You can set alarms to notify you when a tempertature is reached. Several monitors can be added to the panel to monitor different sensors. It is designed to look like the CPU Frequency Gnome applet. This applet used to be called Laptop Temperature Monitor.