I'm not sure that what you want exist, but I've been using epguides.com for exactly that, scouting when new episodes of my favorite series will air. Not sure where they got their info from but it's very up to date and include future dates.
Come to think about it, someone with a good programming skill can easily parse epguides.com (or wherever they got their info from) to get what you want, so maybe this 'original air date grid' does exist somewhere.