Not sure if this is the right forum. Anyway, found this via Consumerist and thought I would share. Some amazing tips there

9. Making a reservation on the phone or in person. Fee: $5-$20
8. Cashing in frequent flyer miles without "sufficient" advance notice. Fee: $0-100.
7. Bringing a pet onboard in the cabin/ Fee: $50-85 (each way)
6. Re-banking frequent flyer miles. Fee: $50-100
5. Checking luggage. Fee: $3-10 (each way)
4. Getting a refund when a fare goes down. Fee: $25 to $200 or more.
3. Flying standby on the same day of travel. Fee: $0-50
2. Paying for lap children. Fee: $10 to 10 percent of the adult fare
1. Getting a seat assignment. Fee: $5-$11 (each way)

http://www.aviation.com/travel/top10-hidden-fees-1.html