It's an awful lot of courses to pick through when you're signing up. Maybe just offer the five most popular to start?
I definitely got in to a "oh this is nice.. and this too.. and these two would be cool..". At the same having the full catalogue of courses available is good of course, but don't overwhelm the first time user.
I would test having the "popular courses" feature, or something like proposed above, just under your headline actually. So it's super easy to see what the site is really about without even having to scroll. That would show off the kind of content you have and even though your name is Highbrow, it might not be clear if you're teaching out nail painting techniques or philosophy when I just read the headline and the feature list you have.
Great idea anyway and nice execution. :)
I've received one highbrow email thus far, and I am happy for reading a good quality blog post instead of having to sift through serps and junk blogs for myself, and also to learn about some new resources in my area of interest. I totally get the one thing at a time, 5 minute per day commitment, I think it's a great idea.