Let's admit it, we all love free design resources and the best ones are free to use commercially! Why? Well, in simplest terms, it allows you to use the work without having to worry about all that licensing gobble-dee-goo and fees. Let's take a look at some of my personal favorite sites for free resources:
Freebies: Commercially free typography
This is my top pick when it comes to typography. Font Squirrel is a site that does all the hard work for you. Instead of scouring the internet for the perfect commercial-use free font. Font Squirrel scours the internet for you by gathering available free fonts from across the web that allow commercial-use.
Freebies: Once a week they give away about 6 freebies that are otherwise for sale any other week. Freebies range from a variety of mediums.
This is a great place to get quality priced goods for free. You don't have to worry about licenses for products because you are stilling 'purchasing' them at a free price. You can also purchase high quality design resources here and even sell some of your own. I actually sell some of my photo transfers from my shop here.
Freebies: Mostly mockups, UI kits, icons, text effects, and backgrounds.
This site has some really great free resources, but be careful about licensing here. Some of the freebies allow commercial use and some are personal use only. This site is my favorite spot to pick up mock-ups. They have a great selection of high quality mockups.
Freebies: Large variety of PSD, vectors, mockups, UI kits, typography, code, stock photos, Wordpress themes, and more!
This is somewhat of a one-stop-shop. They offer the largest variety of freebies. Again, make sure the licensing coincides with your project.