emojipedia - UTF-8 emojis
icomoon - amazing resource! convert custom SVG images to a fast and efficient library of icons, which you can use in your site very easily like
<span class="icon-house"></span>
fontawesome - also great! If you don't want to design or find your own custom icons, they have hundreds of pre-made icons, in various line thicknesses. Use it as easily as icomoon.