There's a ton of places to get download cards these days, but none are self-serve. Card Included lets you build a text or logo card with a simple creator.
The other thing we do is let you build a custom landing page that your customers/fans will see when they go to redeem their code. On that page you can put a large background photo, as well as link to your homepage, twitter, facebook, or tumblr. Here's an example:
Then when you're done, you checkout and we immediately email you a link to download your cards. It's a really easy to use service that I'm pretty proud of. If you have any questions, you know where to get a hold me.