I’ve found the kind of binder that is used (slightly modified) as props on Battlestar Galactica. They’re made by “Keba” and they’re from Sweden.
I believe it is the KEBAergo, 2-inch wide, either letter size or A4 size. (Their line consists of the KEBAergo, KEBAfrost, KEBAecolite, or KEBAesd — but only the KEBAergo is available with black covers.) Based on where the screws are located on the sides, I believe the show used the letter sized, 3-ring style, not the A4 sized, 4-ring style (which has a different arrangement of where the screws are located). But, since these are mainly sold in Europe the A4 size is much more common than the letter sized. The A4 size would be pretty useless to Americans by the way. Domestic colonials will have to track down the letter sized.
The yellow spine is painted with silver paint (but you can spot the yellow leaking through) and the face and back sides have the corners cut off.
“KEBAergo is made of durable polypropylene, able to withstand both moisture and dirt. Simply wipe the folder and it is as good as new! This makes the binder exceptionally well suited for demanding enviroments. The binder is produced with either black or naturalwhite sides.”
The following photo is not the KEBAergo but you can see the general design form of the Keba line in close-up — it’s a match.
So far, no availability in the United States that I’ve determined.
More Galactica binders (click for larger view). The one with the transparent cover is the KEBAfrost, but the rest are the KEBAergo:
More info: www.battlestarprops.com/galactica-binders
UPDATE: Someone else discovered this before me: http://future-past.com/props/ring_binder.php