Since I am really into the MOOC phenomeon, I am constantly searching for free online classes sites, in addition to the "giants" Coursera, edX, etc. Few can even come close in quality, but I discovered an edX powered site that provides free MongoDB training with quality material. You can check it out below:
https://university.mongodb.com/I didn't have a particular interest in MongoDB, but I already finished the developers and administrators courses and am halfway through the advanced one, and I found it very interesting and well made. The only major downside is that there are no slides, so all the note taking is the responsibility of the student, but I already went through many courses where I had to pause videos constantly to take a screenshot or write something, so I wasn't that bothered.