It will set the tone of your site and will frame your words.
You will want to pull that theme to all of your branding materials, like business cards, invoices and etc.
I created my branding materials using the Markr app, which is available for free in the iTunes store.
You are able to create your logo for free using the app and then pay a fee of $7.99 for the image download. Printing is also available through their service at very reasonable rates, with free shipping on orders of over $50.
They can help you create business cards, address labels, stickers and postcards.
Any hardcopy materials that you might need for your business, with the notable exception of letterheads. A service that I highly recommend that they add to their menu.