I used Language Transfer to get started on Spanish, and it was incredibly effective. He connects concepts between English and the target languages that help build vocabulary more quickly. He also explains verb forms in a way that makes more sense to me than the actual Spanish classes I took in school. Duolingo, Rosetta Stone, and others like those never cut it for me for some reason.

I'm now reading webcomics and listening to other podcasts in Spanish to get a feel for more natural conversations. I practice speaking Spanish at work with bilingual coworkers, with the goal to be bilingual myself, too!

(A similar teaching style that I found enjoyable and enlightening is the American Sign Language course by Bill Vicars on YouTube and lifeprint.com.)

I started the music theory course and it is very math-heavy at the beginning. It turned me off, but if that's an interest of yours, it might be a good fit for you! It's a course that is still in the works, so I'm waiting to see the next edition of it to see if I can connect to it more easily later.