I am a nomad, too. My main work locations are the pretty big backpack. (That was the only instance I could find of it online. I got mine at Staples.) This bag carries my laptop (all the time), my traveling files, a couple books, my junior size circa, and my sketchbook before I ditched it in favor of some circa punched blank paper. I carry the backpack all the time.

My traveling files are basically any file folders that I need right now with the most current/relevant stuff. Each of the folders is mirrored back home with less current information for the same file. (A good example of this is when I get handouts in class or graded assignments are returned. Those go into the folder for the class in my traveling files. When I get home, they get emptied out into their more permanent mirror at home.) The files are in a cardboard-isch thing I got at Target a while back that is blue and tan and simply says "notes" on the outside. I haven't been able to find any more which saddens me greatly. I want to get a letter sized rope case from Levenger to replace this part of my system. But, keep this in mind: I do very little with paper and what I do with paper doesn't stay with me long. I have a few sheets of paper in each file of hand-jotted notes that I am using as I move projects forward, but when I am no longer using them, they will go in the mirror files at home.

I do some of my reading on my Macbook, but to be honest, I can't read very well onscreen. That and the fact that I am usually reading something about programming where I need to be typing in examples and such just makes reading onscreen (especially a 13" screen) pretty miserable. I usually print out PDF's duplex and put them into a 1/2" 3-ring binder. If it won't fit, I put as much as will fit and leave the rest at home. I won't get that far in it before going home anyway. If I do get that far, I start removing pages from the front. I figure by the time I am to that point, the front matter won't be as important and can be left at home. If I do need something from that front matter, I can use the PDF as a safety net.

As far as having the right tools available most of the time, I can usually get by with having just a handful of binder clips. Most anywhere (businesses especially) will have a stapler they will let you use or you can get a small one if you're that worried about it. I don't use paperclips anymore, just binder clips of various sizes. If you use the coffee house's stapler, for instance, it's nice to bring them a package of staples every once in a while. Then they will continue letting you use it.

Lastly, I keep my writing utensils pared down. I carry one pen (a Retro51 Beach Cruiser), one pencil (a Pilot G-2 mechanical), one Post-It flag highlighter (hopefully soon to be replaced by a drylighter from Levenger), and a Clic eraser. I'm sure even this could be simplified, but it's working for me right now.

So, my advice would be (And that's why you called, isn't it?) to ascertain exactly what can fit into whatever bag you could reasonably see yourself carrying on a regular basis. If it's big like mine, you can get away with carrying a whole friggin' bunch of stuff. Then figure out a way to get what is absolutely necessary into it. This might need to be taken to extremes in some cases. Do you need to carry that thick book everywhere or are you only going to be working on part of it right now? Maybe you could have it rebound at Kinko's or something (It's surprisingly reasonable.) and then carry only parts of it at a time. Find something to put further constraint on subcomponents of your portable/mobile office. For me, it's that 1/2" notebook. If the printed material can't fit in there, then I have to make a decision. Do I leave the whole thing at home or only take part of it for now? If I didn't have this constraint, I would have my whole bag weighed down with printed PDF's. (I know this is true because that is what led me to get the 1/2" notebook.) In deciding if you need to pack up something, ask yourself if you could readily procure one if need be. The stapler is a perfect example of this. I can't imagine any situation where I would need a stapler RIGHT NOW and not be able to get one. Either it could wait or I could borrow one.

The last tip I have is to buy retractable or shorter cables for stuff. I have a retractable iPod sync cable, an 18" mini USB cable that I use to charge my Bluetooth headset and to connect my digital camera. I used to keep a retractable firewire cable, but it was complete crap so I ditched it. I would like to have a retractable charger for my phone but haven't found one yet.

Snapshot for example: I am sitting at work 1 right now. My traveling files are about 2" thick (container included). I have a ~450 page book (Hillegass' Cocoa programming book) and a ~350 page book (40 Studies that Changed Psychology, blech.), my laptop, my Junior Circa which comes in a little over 1" thick because it's got my checkbook in it. Of course, I have the obligatory power cable for my Macbook and headphones, blah blah blah. But that covers the big stuff. Someone said that my mobile solution wouldn't scale, but I beg to differ. I still have a lot of room available in the bag and the degree to which I live a digital life makes things much more scalable.