I'm hesitant to share my two cents for fear that if everyone tries to do what I do, soon I may not be able to do it.
However....
Like many of you, I want to carry my sensitive camera equipment onto the plane with me. I used to use a modified Pelican case measuring 16x20x10 (# ). However, I hated the attention the case drew, particularly when moving through crowds. I felt like I had a $1000 taped to my forehead and a shirt that says, "Hey y'all! I'm a rich American moron - someone mug me!!"
I now use a hiker's backpack that would never fit inside the metal frames used to measure carry-on luggage. This is an REI backpack that holds my laptop, two camera bodies, and seven lenses - PLUS my journal and several other essentials. Although I am carrying over $10,000 worth of equipment in just this one bag, I never worry about getting mugged when I walk down the street bc the pack itself is worn and dusty. I _almost_ look like a bum.
My second bag is a Columbia shoulder bag, the same style bag you would see a bike messenger use. As I carry this bag slung across my shoulders, it appears to be just wide enough and just tall enough for the carry-on measurement frame. However, were they to look at the depth, they would see I have snuck on several more inches. I carry my housing in this bag, plus an 8 inch dome port or other things. I also carry my airline tickets, passport, and other valuables in this bag.
(http://www.cerfbag.com/columbia_dev/product_detail.asp?id=91)
Carrying your things in a roller-bag is great and convenient, but I prefer to carry it on my back - but here is the catch - I sometimes carry 40+ pounds on my back. so this solution may not work for most people.
Another friend of mine uses a roller-bag specifically designed for photo equipment with the dividers and all, but I can carry a LOT more than him onto the plane because of the way I can adjust things within my pack.
If anyone ever asked me to actually stick my backpack in the measurement thing, I would be flat out screwed, no question about it. Fortunately that hasnt happened yet. (knocking on wood vigorously)