I've been exploring some of the learning tools available on your site, and I have to say that many of them have sort of a half-finished feel and are extremely frustrating to use. I'll just list a few:
1. When using the Deck Manager, if I type a word into the search input on top, I have to press return in order to submit the form. Why not just have the page update the results in real time?
2. Deck Manager again. When I search for a word, EVERY word in the results is checked by default. I have to uncheck them all every time and then re-check the one I want.
3. If I am Editing a flashcard list and press the "Add New Cards" button, the list I was just editing is not selected in the "Add items to" selector, which means that until I get used to it, I keep mistakenly adding the words to "New deck" over and over.
4. There doesn't seem to be any way to add words to a deck that are not found somewhere in your own lesson materials. You have a link on the vocabularly lists page that takes us to "Custom Lists", but for some reason this appears to be an external site and even then what you wind up with is a separate ist with no apparent way to import it back into the tools on japanesepod101 (such as flashcards).
One more: when I search for a word in the "Deck Manager", oftentimes the same word will appear multiple times in the results (sometimes with slightly different romaji spellings). For example, try searching for "八月". It turns up three results (and again, all are checked by default).