Yes, I believe it's known as rucking and is a staple of military training (note: so I've read, I have no personal military experience).
Dan John talks extensively about loaded carries if you want to try something slightly different. These are great for increasing work capacity, burning more calories, increasing strength and endurance, and just making you tougher all round (because hugging a sandbag to your chest and trying to walk while it's trying to crush you is character building).
In short, if you get bored just wearing a weighted backpack, while walking, you can try hugging it to your chest, carrying it in one hand (note: swap hands at the half way point), carrying it overhead (you may get weird looks from people), carrying it overhead in one hand (likewise), carrying it across your shoulders, carry it on one shoulder, put it in a sled and drag it, put it on a sled and push it, put it in a car and push the car, put the backpack on a friend and give the friend a piggy back... ok, so I'm getting a bit carried away, but you get the idea, there's several different things you can do with a loaded backpack :)