actually, there is so much slang in most of our lesson already.
we've gotten e-mails from japanese teachers who've been overseas for a long time saying "we don't use those words!"
one interesting thing about slang (and this also makes it difficult to cover in a cohesive way) is that it varies between social groups. for example, ギャル in shibuya speak differently than オタク in akihabara. of course, there is slang that is mainstream, but like i said, a lot of that finds it's ways into jpod conversations naturally. i guess the hosts just don't clearly point out "hey, this is slang!"
maybe in the form of a culture class, we might be able to do something like this.
so, your idea is noted! just give us some time to think of an interesting way to go about doing it.
marky