i have the tamrac velocity 7x. it is a sling bag, which is good for walking around and can hold a good amount of equipment. i hold my D80, 18-135mm, 50mm, and sb-800. i can also throw is some extra memory cards, cleaner, etc. it holds all that and not much more.
i also have the Kata DR467. it is a backback which holds more stuff than the tamrac. it has a laptop compartment, a top half which can hold a few odds and ends, maybe a windbreaker, small lunch, etc. the camera compartment holds all my equipment and could probally hold another lens if i really wanted it to. its a little big and bulky at times, but it holds its own. i used it on my trip to israel and im glad i had it. it also comes with a bright yellow rain cover. its good, but really bright.
i dont have any pics with my equipment in them, but they are both good bags.
For mobile shoots I just put my equipment in my Timbuk2 messenger bag. It's much easier and faster to access a lens if I need to or anything else.
I used to have the standard Canon equipment bag, but it was bulky and hardly had enough space for me. The Timbuk2 is working out great and it makes the equipment feel lighter than the Canon did, it's much more comfortable.
I also have the Tamrac Velocity 7x, and I'll have that on my back most of the time (with the strap across my body), and can easily swing it around to my side to pull out gear. When actively shooting, the Velocity will be on my back and the D40 will be hanging around my neck.
Anyone using the Zing line of camera wraps? They're neoprean "skins" that go around the camera. I'd thinking about getting one with my D40 so I can carry it right in my messenger bag without fear or banging it up.
Another vote for the Lowepro Slingshot range, I have the baby one, plenty of room for a couple of extra lenses and filters, plus enough room for cables and chargers, and a neat waterproof cover built it.
Very comfortable and very easy to use, it's designed to rotate around your shoulders and has side access for the camera without taking the bag off.
I'm another Slingshot 200 user. I find it has lots of room for 3-4 lenses plus all the other stuff you can think of taking. Also if you are out shooting something in specific and don't need a variety of lenses you can rearrange the compartment so that you can store food, or a sweater or whatever. I just wish it had a pocked on the outside for a waterbottle or something.
I use the Lowepro FastPack 250, in a sling like setup. I use only one strap, and sling it over my left shoulder. Gives you quick access to the camera, and laptop, though that is more cumbersome, and I usually just set the bag down to get the laptop.
It holds my 400d, with grip, and this Sigma 24-60 with hood attached. Also a canon 55-250 IS lens, a 550ex flash, cleaning kit, caps etc in the camera area at the bottom. In the top section it carries my IT tool kit, some CDs etc, and laptop accessories. And my MBP 15" in the laptop sleeve section. When I have everything in it, its heavy. If I do carry everything in it, I use both straps. I am glad I bought it, and it has worked very well for what I need, but the left shoulder strap, where the lowepro logo is, has ripped the logo on one side. I am sure its because of the weight I have in it, and using only one strap.