If you are looking to create business cards, flyers, postcards, tri-folds, more, I've listed a few of the services I have used. For branding/swag type items or if you are an artist looking to sell your designs on different products I've listed a few services for your review. Most of the different service providers have templates you can download so you can start the layout process pretty easily.
Online Printing Services:
Products With Your Design: