For holding paper, there are two common options. You can go with a spiral notebook, which allows you to fold it back on itself (as opposed to two pages wide), but you only really have the paper that it comes with. You can go with a binder and add what you want, but either the paper has to come out, or it takes up the space of two side by side pages. Either way, it only takes one size paper.
Enter disc binding.
Disc binding allows paper to be inserted and moved around like a three-ring binder, but can be folded back on itself like a spiral notebook. It also allows for pages of various sizes to be incorporated into a notebook. A pocket-sized shopping list can be put into an A4 notebook as just another page. The office supply geeks I follow on twitter and I have been talking about this off and on for a few months. Mostly, it’s been noting that we are all fans, and exchanging various tips.
Where three ring binders and spiral notebooks use a closed hole in the paper to thread a loop though, the holes in a disc binding are have an open slot smaller than the main hole. This has been described as a “mushroom.” To bind the paper, discs are inserted. The outer edge of the disc is rased, so the paper is gripping the ring. The rings are about an inch apart. This allows sheets of varying sizes to be inserted into the notebook. The sheets can be re-arranged at will, while still being able to fold back on itself liek a spiral notebook.
The main disadvantage is that the system is propritary–only a handfull of companies make components for it. The two key disc binding lines in the US are Circa by Levenger, and Arc from Staples. I’ve seen disc bound notebooks from Clairefontaine and the Container Store sells a line as well. The Circa and Arc systems appear to be compatible with one another (and we’ve gotten paper from the Container Store as well). Since it does not work by default with material from the office supply cabinet, it does present a higher cost of entry.
I started using a disc bound notebook for work about a year ago when I got a Circa starter pack from Levenger. Since then, it has been augmented with parts from Staples. In particular, I got the Arc punch, which is both cheaper than the Levenger product, and, quite frankly, I like the design and action better. This allows me to put any sheet in my notebook. The official intent is to put printed documentation in there, which I do (such as process documents for work). However, it also allows me to harvest notepads of my choice for paper to fill the notebook with (I’m a bit fussy about my paper).
A coworker of mine also uses this. She described it as “a SmartPhone for notebooks,” given the flexibility. I think that’s a great description. It allows paper to be mixed, matched, and moved, while retaining the compactness of a spiral notebook. I definitely love mine.