ProxyChecker  

Open web proxies can be used for a number of things - surfing anonymously, making anonymous posts to message boards, some of them even let you send email or make arbitrary connections to other hosts. Now you can ensure that your own list of proxies is never outdated by using ProxyChecker! This script will go through your list, checking each proxy to determine whether or not it's active right now, and if so, what the latency (response time) of the proxy is. With this output you'll have no problem spotting closed proxies or figuring out which of your proxies is the fastest.

Price: $35

   Traffic Bar  

The script displays statistics and/or graphic bar showing the current bandwidth utilization.

Hosting Requirements: Linux
Price: $15

   kimono  

kimono is a network service monitor similar to sysmon. it stores all data (by default) in XML format making it very flexible in its use. the data is collected through a daemon. the code is object-oriented and easy to extend to suit your needs.

Hosting Requirements: Unix, Windows
Price: Free (GPL)

   aNTG - another Network Traffic Grapher  

aNTG is a a program that collects and displays network traffic statistics on a Linux-ish machine.

Hosting Requirements: Unix/Linux; PHP
Database: MySQL
Price: Free (GPL)

   Fuzzy  

FuZZY is a network analyzer that is designed to act as an Acceptable Use Policy Infraction Detector (AUPID). It is a tool that will allow Network or System Administrators to monitor and manage their user's activies over the network.

Price: Free (GPL)

   PortPeeker  

PortPeeker is an extremely flexible and fast portscanning script. You can scan a single host or a range of contiguous IP addresses, and you can scan each host for a single port, a range of ports, or a list of specific ports you determine.

Hosting Requirements: *nix; PHP 4.2+
Price: $39.95

   Realtime Bandwidth Monitor  

PHP script for realtime monitoring of the current server incoming and outgoing traffic. Can be used to trigger special events on too high or low bandwidth consumption.

Hosting Requirements: Linux
Price: $15