"Wikimedia Commons is a media file repository making available public domain and freely-licensed educational media content (images, sound and video clips) to everyone, in their own language. It acts as a common repository for the various projects of the Wikimedia Foundation, but you do not need to belong to one of those projects to use media hosted here. The repository is created and maintained not by paid archivists, but by volunteers."
Think of everywhere clipart can be used in your restaurant: menu, cups, napkins, table toppers, newspaper ads, flyers, coupons, television commercials, door hangers, signage, window clings, temporary tattoos, coloring books, doggie bags, flags, banners, receipts, letterheads, business cards, refrigerator magnets, postcards and much more. Each and every one of these is an opportunity to build your brand and consistency is the key. The clipart elements you choose should have a consistent look so they reinforce each other and the brand you're building.
All of these items can easily be created with artwork found online or on a computer. The average person should be able to locate all of the images needed to create such artwork in a few minutes and simply use Clipart to include them in their document.