QoS of the ISP

Test the Quality of Service of your Internet Service Provider
All broadband speed test
Flash plugin based speed test
Line quality test
Tweaking the TCP stack (java tweak tool; tweaktester, receive window)

Free networking tools:
PRTG traffic grapher 6

PRTG Traffic Grapher is an easy to use Windows software for monitoring and classifying bandwidth usage. It provides system administrators with live readings and long-term usage trends for their network devices. The most common usage is bandwidth management, but you can also monitor many other aspects of your network like memory and CPU utilizations.
Local IP lister
Local IP Lister shows the list of IP addresses that are configured on your PC and that can be used for the internal webservers of
PRTG Traffic Grapher and
IPCheck Server Monitor.
The small tool doesn't need any installation, just download and execute...