I am currently working on some USDF University online. I also signed up for the Coursera.org/University of Edinburgh equine nutrition course (free - there are a couple threads here mentioning it) which will be fun. I've worked with people from the University of Guelph, which offers online equine courses, and have heard good things about it.
I am doing all this just for the fun of it (not to advance my career necessarily); it is a topic I feel passionately about, after all. Are any of you involved in online courses? What do you recommend?