I have been talking about ethics when it comes to whether a site designer should or shouldn’t put a hyperlink back to their site at the footer of anew sites pages that they have just built. Here is more on the subject from SEO Roundtable
Direct Marketing Observations
Digital and Social Media Marketing Insights from Marc Meyer
Direct Marketing Observations 
Google apparently gives little wait to links in the footer section of websites anyhow. The links themselves are mostly from off-topic sites anyway. So the SEO value is minimal. But we do it as a company, I think it is a fair way of getting a bit of advertising. Our clients certainly do not complain.