Where to get free icon images

This is the MetallicIcons site provided by Google. You can download it yourself and use it as a web font. (Copyright free)

There are other sites besides those provided by Google. It's free to use it personally, but you need to check the copyright when you use it commercially.

Additionally, IconFinder is also good. There is a fee/free depending on the icon, and the free icon is of very good quality. I heard that designers use it a lot, too.