Icons can really make a difference on a website. You can decide to design them yourself in Illustrator or Photoshop but you can also find great icons that fit your website for free on the internet.
Below I listed a couple of website with good selections of free icons.
Great selection of icons, with a lovely interface.
Icon font, simple flat icons. I hope this helps you find the prefect icon for your website. Drop a comment if you know some other good websites with free icons!