A list of some useful links that I find handy to use.

Oz Broadband Speed Test.
You can check your Internet speed here and find out what you are really paying for.

Speed Guide.
Here are some useful tools that you may find interesting.

Gibson Reaserch Corp.
Great site to test your Internet security (Shields Up).

Broadband Comparison.
Compare Broadband and Wireless plans and features here.

W3C Markup Validation Service.
Validate your website code here,

CO2 Trees.
Some good articles on Carbon Emissions and Carbon Credits, worth a look.

MX Toolbox.
All of your MX record, DNS, blacklist and SMTP diagnostics in one integrated tool.