Take your icon game to the next level. Check out Fonticons, from the maker of Font Awesome.
             

fa-key · Unicode: f084 · Created: v1.0 · Categories: Web Application Icons

After you get up and running, you can place Font Awesome icons just about anywhere with the <i> tag:

fa-key
<i class="fa fa-key"></i>

Looking for more? Check out the examples.