TripShock! (Top Choice)
TripShock.com not only has a wide selection of activities, but it has several great deals and promo codes are always avaialable. Go to TripShock.com to view a list of their activities in Panama City Beach and the best deals.
Visit Panama City Beach (TDC)
The Panama City Beach tourism council has a great website with several deals. Check it frequently for updates on tour and activity savings.
Groupon usually has 50% off deals for activities and attractions for Panama City Beach. Subscribe to their email list and just wait for a good deal.
SEE magazine is a visitor publication that you can find in most hotels and restaurants in Panama City. There are usually discounts to restaurants and activities in these booklets. They are not usually big deals, but they will help save a few dollars on your activities.