May not seem like a big deal, but I am absolutely in love with this portable digital luggage scale. I added it to my gear earlier this year and it has saved me so much money and time at the airport that it has paid for itself at least 6 times over already.
When I travel, I usually have my camera bag, at least 1 large duffle, with a second larger duffle the first one fits inside (so it is essentially one bag covering another, and it I am shooting, I also have my gun case.
My camera bag also has my flashes and computer, so I can easily get that thing to feel like a ton of bricks.
Each checked in bag has a 50 lb limit before you are charged extra fees, so having this scale, both at home and on the road, I typically start off with my gun case, loading as much "accessory" stuff in there as possible. Scopes, magazines, ammo, etc. Mostly gun related stuff, but Ive also thrown in other things.
Then I weigh my main clothing bag, determine how much extra weight I have, and then typically put the heavy lenses in there and everything else I can in there right up to about 48 lbs.
Camera bag now mainly has computer, camera bodies and is super light.
Now every time I check in, I am 1-2 lbs perfectly underweight and dont have to deal with the hassle of moving things around or paying extra fees.
If you travel a lot, especially if you tend to come back with more than what you left with, this is a must have!
This is the one I use: CLICK HERE For Michael's Portable Digital Luggage Scale