Very nice idea.

On the main page, consider listing the languages, rather than using flags. Languages and countries don't always correspond one-to-one; many of the flags you have link to the same language, and conversely there are multiple languages spoken in some countries. A language list would be both more compact and more directly convey what people want to look for, rather than making people indirect through "I want to learn more of language X, which of the several countries speaking that language should I select, and does it make a difference?".

(That said, if you later expand to cover regional differences in accent, distinguishing between countries seems useful for that.)