I took my beautiful white discbound notebook to GenCon with me this year as my be-all, end-all GenCon reference. I loved every minute of it. That makes four well-tested, well-loved discbound notebooks that I use currently: GenCon, Rifts campaign, player notebook, work notes.
I know what you're thinking: "those are those girly things crazy scrapbookers use, why would I want to touch one?" Good question; they have definitely been marketed to and adopted by a specific niche of folks. The answer is that they combine all the good things about three-ring binders and spiral notebooks. It is easy to take things in and out, move things around, punch holes in just about whatever to stick in there, etc. Because the rings are close together, you can punch an index card with stats on it to pop it in and have it hold securely. Take the card out for use in your game, put it back in later. You can add pocket folders, dividers, sheet protectors, and pretty much anything else you might add to a regular binder. The pages are surprisingly secure, too. My Greylord Magiya note pages, for example, rip through the holes almost immediately upon use so they're kept in the binder with those little reinforcement stickers and hope. I haven't had any issues like that with pages in my discbound books (save for an experiment in creating my own pocket folders and those lessons have been learned).
Expect more on this in the future as I've become completely obsessed. In the meantime, here's some resources for you:
Levenger makes some classy, high quality discbound products in their line they call Circa. I have been especially coveting these
discs that can hold your pen.
I love the look of
Dokibook's Discagenda discs with a hole in the center of them. Some of their stuff is a little...flouncy for my tastes but it's hard to say no to stylish discs in solid aluminum.
Most of what I get is the
Arc system from Staples. Everything's inexpensive and good enough quality for my purposes. Staples is also home to the
Martha Stewart discbound line, which has some nicer covers with elastic built in and interesting colors.