Reddit mentions of Vela Hardcover Lab Notebook / 9 x 11.75/128 Pages/Grid

• Timbuk2 laptop messenger (it rains a lot here in Oregon)
  
  
• Engineering Notebook to keep track of everyday stuff
  
  
• Nalgene for hydration (helps that we have free coffee/tea/soda at work)
  
  
• G2 0.5mm pens
  
  
• TI-36X Pro in the event I need it
  
  
• Tackle box with sample prep equipment (tweezers, scribes, etc)

If you're going for a composition-notebook style, I'd recommend getting one with graph-ruled paper, rather than plain lined. You can still use the horizontals to write on, but you can also use it for drawing maps, etc, without having to use separate pages.

If that appeals, you can also get something like this,where the pages are pre-numbered, and there's an included index section at the front. Or if you don't want to keep all your notes in one place (different campaigns, etc), a three-pack of Moleskine grid-ruled notebooks is pretty cheap ($13 at the Barnes & Noble where I picked mine up)

As for what to put in it, I'm with everyone else:

• More encounter data than you plan to use, so you have extras
  
• NPC names, town names, small references you make to the party that could turn into quests later (see the post from a few weeks ago about 'adventure seeds')
  
• In the same vein, anything the PCs do or say that you want to come back to haunt them in the future
  
• Magic items you want to give the party at some point
  
• A list of person, place, and thing names, in case you have to pull one out of your ass mid-session (I got caught flat-footed and wound up having my PC's rob "Duke Who's-his-balls" one night - despite retconning a name in for him later, the Players insisted on him being "Duke Housibahls" forever)
  
  And, for fun, litter your notes with rulebook page number references that refer to abilities, monsters, NPCs, etc that your players either really want or really don't want to encounter, just in case someone goes snooping. Only you know which ones actually matter
  

Depending on what type of science courses you take, I'd recommend our stuff. Our paper is water-resistant, so you can spill on it without consequence. It works great with ballpoint pens, as well.

Let me know if you want a little sample book to try out.

I've also heard good things about these types of notebooks (1, 2, 3). I've tried something very similar to the Scientific Notebook Factory one and liked the feel of the paper.

VELA Series-E2, Engineer Research Notebook.

VELA Series-E2, Engineer Research Notebook, 8.5 x 11 inches, 128 Pages, Hardcover, Permanent Smyth Sewn Binding, Class-2 'Optimized' Notebook (5x5 Grid Variation)

NOTE: The Amazon page makes no mention of this notebook meeting any ISO standards for archival-quality paper, and only says "acid-free for archiving".

Size is the main reason. I have larger notebooks for other things. In fact, for projects and the like, I use lab notebooks with sewn in pages that are already numbered, etc. (Something like this.)

I keep a small field notes notebook in my back pocket to scribble down lists or make notes of things that I need to transfer to my larger notebook if I don't happen to have that one with me.

I bought a couple of larger size Field Notes notebooks and they tend not to get used because if I'm carrying something large enough to hold them, I just carry my project notebooks instead.

I've been using this. The paper quality could be better, but it takes every ink I've thrown at it without feathering and only the occasional bleed. And it's sexy as hell.