Q-tips: they are cheap (box of 300 costs 3 or 4 bucks), easy to find, are useful to clean your ears and actually teeth in a pinch. Also they can be tattered on the ends to let them fit into almost any small shallow crevice and therefore make excellent computer cleaning tools and tool-cleaning tools. I keep a small pack of them in my work drawer, at home, in my car, and in my shower bag.
20 oz. Coke bottles: They hold the perfect volume for me, and they are very tightly resealable, which preserves the coke and keeps anything else you store in there safe if you reuse the bottle. Coke is a good drain-cleaner and sink-cleaner, and I have found it's a pretty good wound-cleaner too. Plus, 20 oz of coke will turn one of those small bottles of Jack Daniels into a Friday-night awesome kit. Plus, if you poke a small hole in the cap, the polyethylene terepthalate is weak enough to let you make a pretty decent squeeze-bottle out of it. Finally, if you fill the bottle about 1/3 from the bottom with liquid, it makes an awesome and fairly accurate projectile which you can kind of flip-throw by holding it by the flare near the cap as you wind up the throw.
I am in the process of making a change possibly from my folded-up notebook paper to a moleskine, over the next however long it takes to fill it up or to destroy it. The paper is by far smaller, and a little bit more comfortable (but I don't notice the moleskine in my back pocket so much now), but the MS has more room to write in and seems to be more impervious to lint and destructive abrasion by denim. The biggest impediment I have to using it is some strange aversion to writing in a non-spiral notebook that I've always had, rooted in some perverse aversion to 'sullying' the thing with non-coherent scribbling and notes, instead of some masterpiece novella or laureate-grade poetry. Why this is only applicable in non-spiral notebooks I have no idea. I use these types of notebooks as lab notebooks all the time with no problem. Anyway, the honeymoon continues.