Back in the day, checking your bag on a trip only cost you 20 minutes of your time after a flight. Now you’re lucky if it only costs you $20. With rampant theft, high bag check costs, and overhead bins filled to the brim, learning how to pack efficiently matters more than ever. With the right strategy, you can fit everything you actually need into the seat in front of you. More » 
(from Lifehacker http://lifehacker.com/5990659/how-to-fit-two-weeks-of-luggage-under-the-airplane-seat-in-front-of-you)
