Hmm. I see those around sometimes, or see the Ichthus™ symbol on businesses' ads or signs. It always lets me know where not to do business.

Not that I think I'm going to get screwed, but I'm very much against the idea of using one's religion as a way to get business, and the idea of preferentially doing business with people of one's particular religious bent. So I tend to avoid businesses that engage in or promote either practice.