Osmius
- Allows the monitoring of heterogeneous systems using multi-platform agents distributed over a network. Includes news, downloads and a development blog.
- http://www.osmius.net

Zabbix
- Software for application and network monitoring - logging, monitoring, capacity planning, availability and performance measurement, and helpdesk information. (C, PHP) [POSIX]
- http://www.zabbix.com/

Calamaris
- Parses the logfiles of a wide variety of Web proxy servers and generates reports. (Perl) [Linux, Unix]
- http://cord.de/tools/squid/calamaris/Welcome.html

Htmlobserver
- Web page checker based on regular expressions. (Java) [Linux, Windows]
- http://home.arcor.de/hirnstrom/htmlobserver/index.html

squidefender
- Perl script which parses for attacks a squid log file. Allows to run commands or automatically notify the attacker's ISP upon trigger.
- http://www.jeroen.se/squidefender.php

Fast Track Systems Monitor
- A general purpose monitoring engine for use by home users and system administrators (Perl) [Unix, Win32]
- http://ftmon.sourceforge.net

RackView
- Assists in visualizing a Data Center's computer rack layouts by creating a web page with HTML tables to show a frontview of the racks. Included are brief commandline and CGI scripts to demonstrate its implementation. (Perl) [Linux]
- http://rackview.sourceforge.net

Ntop
- A tool that shows the network usage. It can be used interactively, or in web mode. (C) [GNU/Linux, Unix, Windows]
- http://www.ntop.org/ntop.html

Iperf
- A tool to measure the maximum TCP bandwidth between two points on the internet. (C++) [Many platforms]
- http://dast.nlanr.net/Projects/Iperf/

Resource Utilization Explorer
- RUE is a monitoring/profiling tool for any Java based server. (Java)
- http://rue.nolimits.ro/

NISCA
- A network interface traffic statistics reporting and graphing tool. (PHP)
- http://nisca.sourceforge.net/

Network Grep
- Ngrep is a pcap-aware tool that will allow you to specify extended regular expressions to match against data part of packets on the network. (C) [GNU/Linux, BSD, Windows 95/98/2000]
- http://ngrep.sourceforge.net/

Netload-Applet
- A network load monitoring applet for GNOME. (C) [GNU/Linux, FreeBSD]
- http://netload-applet.sourceforge.net/

Fireparse
- Emails a report of all packets that have been logged by the kernel's ipchains or iptables packet filtering subsystems. (Perl) [GNU/Linux]
- http://freshmeat.net/projects/fireparse/

NetSaint
- An active network monitor with plugins to monitor several types of services, e.g. ftp, http, tcp port, disk space. (C) [GNU/Linux, Unix]
- http://www.netsaint.org/

CoCaLoRes
- Resolves IP numbers to hostnames like in Apache, Squid, or other logfiles. It is able to cache lookups in a file. (Perl)
- http://cocalores.sourceforge.net/

AWStats
- A web server logfile analyzer that works as a CGI and/or from command line, and supports multiple languages. (Perl)
- http://awstats.sourceforge.net/

Anteater
- A log analyser for MTA logfiles (for example sendmail). (C++) [GNU/Linux, Unix]
- http://anteater.drzoom.ch/