There's not really any specific ones that I know about. The problem is that it's a relatively new disipline so it's only starting to creep into university courses now. Another problem being that it's frequently changing, so any course taken over 2-3 years ago would probably be out of date. I guess you'd be best taking some general courses in web design, valid HTML, marketing, and information management to prove your basic skills, and then proving your SEO ability though previous work. There probably are SEO courses and certificates around but there's certainly nothing close to an industry standard.