You all have probably seen Clark Howard's flight tracker, but I just started using it a lot recently. It helped me land a killer deal to Paris in high season (no joke - I saved a couple thousand bucks from what I was actually budgeting). Sometimes the deals are a little out of date, but most of the time I can find them. For non-Atlanta flyers, there is also a webpage where he tracks national deals, but they are more sporadic.
For non-Atlanta travelers:
Re: PSA: For people who fly out of Atlanta