SpamCheetah is a network-level spam filtering solution built around OpenBSD greylisting, tarpit, and blacklisting. It comes with a Web interface and requires zero administration. It does not allow spam to even land in your network, thus saving you precious bandwidth. It does not have the 'false positives' problem of losing legitimate mail.
TIPP is an IP planning application for network departments of organizations with medium- to large-sized networks. While providing all the necessary functions for keeping track of your IP and network allocations, it combines simplicity of design and use with a clean and thoroughly modern look and feel.
OpMon is a network and system monitoring application based on Nagios with extended support for capacity planning, SLA, SLM, network discovery, service catalogs, report schedule, Davinci, a dashboard builder, and much more. OpMon provides a GUI for Nagios as well as full multi-language support. The license to use the opmon proprietary modules is free for 2 hosts and 20 services. OpMon comes with many open source applications like phplogcon, Nedi, ntop, nagtrap, OCSInventory, OTRS, and opcfg.
Panoptes is a scalable, extensible network and host monitoring tool. It includes a dynamic Web management interface based on the Dojo toolkit. It monitors SNMP, TCP port availability, ICMP, HTTP response and content, and SSL certificates internally. It supports monitoring anything else via shell scripts. It also includes a packet capture tool for discovery of hosts, port, and OS.
Nmap Observer is a small application that shows the results of an nmap scan in a Web interface. You just need to specify the range of the network on which the scan is to be performed. Then the scan results are saved to an XML file. Nmap Observer parses the results, saves the results to a database, and shows them to you.
Watch My Network is a script that detects network devices connected to your network, and saves details of these devices to a MySQL database. You can access this data with a Web browser. This user interface has tabs like "Browsing History", "New Device Control", "IP - MAC Changing", "Vlan Search", and "Operating Systems Search in My Network". This program can be run repeatedly via crontab.