I second that idea, it would be invaluable.
Another thing which would be great, would be to link the grammar bank and word dictionary to the podcasts/PDFs.
Like your find a word in the dictionary on the site and its tagged the first lesson etc that it appeared in, this would be a fantastic reference!
Also, an idea, which I'm pretty sure that you haven'd done, would be too tag the grammer to the lessons they appear in.
This would be a fantastic addition! I know it's a lot of work, but you guys have a done a great job so far! Merry Christmas to you all!!