For example, if you often surf the internet free in public places, you may realized that your Internet usage blocked after the allocated usage time and bandwidth. A practical solution to this is to change the MAC address of your Laptop, so that your system will be appeared as a new one.
You can change the MAC address of your network card manually through the network interface card properties or via a simple, free application called Ryll-MAC-Editor (in Windows).
Ryll-MAC-Editor is a very easy to use tool. Just download and install it. Run it, select a network card, and click ‘Update MAC’ to change the MAC address.
You can always reset the changes to default by clicking the ‘Reset Default MAC’.
If you prefer manual method, here is how you can do that in Windows 7.
Open device manger (Right click Computer – Manage – Device Manager) and locate your network interface under the ‘Network adapters’ category. Right-click on it, select Properties and then select the Advanced tab.
Select Network Address from the properties and choose the option Value and type custom MAC address.
The MAC address is in form of twelve digits, so you can type anything like 123456781234. Click on the OK button to save the settings.
Both the methods above, you may have to restart your computer for the changes to take effect. [via]