Disclaimer right up front - no pictures as I'm on travel.
I recently bought a Western Flyer with an assortment of pouches, key straps and what not. One reason I bought all the sizes was because it was difficult to determine what fits. Accordingly, I thought I'll try to explain what I'd put in the pouches.
First impressions: Very nicely made and not expensive for the quality. The clear pouches have an amazingly plyable clear material that almost feels rubbery - a thicker version of the clear protector things that come on virtually every piece of electronic gear we buy to protect the displays from getting scratched in transit.
The clear material doesn't seem overly affected by heat or cold. I left one in the car during record heat in Colorado yesterday (93 degrees with about 2 percent humidity - quite comfy for somebody used to DC) and I stuck another in the 'fridge overnight.
The one from the car was very plyable but didn't seem the worse for wear and the one from the refrigerator was a bit stiff but softened right up once it got to room temps.
Like the clear electronics protector stuff, this clear material will stick to smooth things, sometimes making removal of object a bit difficult - it'll stick to glossy magazines.
Clear Mini - great for spare cell phone batteries. Don't co-mingle these with other metal items as the li-ion batteries are a fire hazard in general and are a specific threat to airplane travel. I stick a post-it flag over the battery terminals so that they won't short out if they get jostled and end up terminal to terminal. The mini easily holds three Blackberry batteries and my pack of post-it flags.
Fabric mini - all the little stuff that you might need, paperclips, post-it pads (I love that post-it stuff.) Business cards also fit and I use one as space for my extra cards.
Clear small - I use this as my "mini 3-1-1" bag for my little tube of Blistex (lip balm - you need it here with the low humidity,) Neosporin (anti-bacterial cream for cuts) small Purell (hand sanitizer) and the little tube of toothpaste that you get from the dentist. As a guy, that's all the liquids/gels I'd need in a pinch.
A note about 3-1-1. While TSA "requires" a quart size "ziploc type bag," this works well as it is immediately obvious that the stuff in the smal pouch would easily fit into that quart bag - one reason why the clear quarter cube works as well.
Fabric small - easily fits a portable sized hard drive and requisite cable. If you don't do that it'll fit a travel charger or two (where the blades fold, like the Blackberry travel chargers or my favorite iGo charger) and a USB cable and a Blackberry charging cradle.
Clear medium - I was having a bit of a problem with this one. I suspect most people would use it for receipts, copies of travel documents (you do make copies of everything in your wallet [with phone numbers for the credit card companies,] right?) or similar stuff. I don't like folding receipts so I don't use it for that.
It also works well as a larger 3-1-1 bag. Here I put all the stuff from the small 3-1-1 bag plus 3 Gotoob tubes (great stuff. They are completely leakproof refillable soft squishy translucent tubes for lotion, shampoo and the like. They come in 1.5, 2 and 3 oz sizes. They also make plastic "jars" that are easy to open by hand but won't come open by themselves. The jars are good for all that girly cream stuff that comes in jars bigger than 3oz)
Fabric medium - all my electronics (3 Blackberries, a cell phone, pager, pedometer) and my watch and wallet for going through the TSA screening process. Once at the gate, I can just pull out this bag and put myself back together.
Clear large - easily fits a letter size/A4 manila folder with paperwork or just loose papers. I use it for all my receipts so nothing gets folded. It'll hold more than a quarter of a ream of paper (but less than a half) or about 125-150 pages.
Fabric large - I didn't get this one (but I think I will) as it would be great for what I call "destination documents" - the maps, event tickets, confirmations and what not that you probably never need (confirmation of reservations) or that you certainly won't need until you get to your hotel.
What clear isn't good for:
I wouldn't use clear for sharp objects or try to overstuff a clear pouch. I suspect that putting a charger into a clear bag and then stuffing it in your bag will permanently deform the clear material - maybe I'm just paranoid but it seems more fragile than fabric and more suited for thin flat items or those things you really have to see (like the 3-1-1 stuff.) smooth stuff will stick to the clear material making a bit difficult to remove.
A note on the key straps:
I connect my "electronic" pouches together with a keystrap. If a checkpoint seems particularly picky or they want to look in the bag, then you can just put out the keystap with the attached puches for inspection.