It would be superb if at some point there is a lesson that explains to you flat out the proper grammar/sentence structure of a given language, would make it much easier.
Maybe there could be also some links to external pages... is it possible to make some partnerships with grammar sites?
Some grammar lessons or 'tips' pages would be nice. I think Spanish and German have these in the first lesson. Also, references to external resources would be nice.
The English Grammar for Students of ...series are pretty good, eg at http://www.europeanbookshop.com/series.php?xkey=EGFS&entrydate=999999&filter=none&display=full or Amazon