

Need feedback on my startup website - derekhuether

I am the creator of HueCubed, a flashcard and visual feedback engine. http://HueCubed.com is my parent website. The site name is completely ambiguous but I am using it as a launching pad to my product sites and to build a brand. I've since launched 2 product sites using the engine.  http://PMPrepFlashcards.com is a very niche market that services aspiring Project Management Professionals (PMPs). Just yesterday, I launched http://K12Flashcards.com to test the extremely broad market of K-12 students.  
The question:  Is it more important to centralize content on the home site or should I be building content on each product site (besides the flashcard product).  I'm trying to see which site will get traction, before going all in.  Any feedback would be greatly appreciated.
======
Rust
Clicks:

<http://HueCubed.com>

<http://PMPrepFlashcards.com>

<http://K12Flashcards.com>

