I do have some nice sketchbooks, but most of the time inspiration and creativity happen when I am not near them. At one time I must have bought about a gazillion spiral one subject notebooks for the kids for school, so I have lots of them at home and the studio. They are usually what I sketch ideas in. Scraps of paper, paper bags and napkins have been called into use in a pinch. I took a lot of images at the LA Co. Museum in the fall, so I will browse through those for ideas. My daily list of things I want to make or throw is another place that will get little sketches.
When I go to workshops, I generally don't take notes anymore, unless I think I will not remember something AT ALL. Mainly I try to absorb someone else's technique, compare mentally to what I know, and then figure out a way to use their ideas to enhance my own, rather than copy their work. As my skills have improved, I realized there are a lot of ways to make pots that I am familiar with, so I don't feel like I have to document things as intensely. Sometimes I have found that you can get so bound up in a thing that is supposed to free you (like sketchbooks or computers) that you actually lose sight of the purpose.
My dad used to have a big poster in his office that said "When you are up to your rear (insert your favorite term for hind quarters here) in alligators, it's hard to remember that your original purpose was to drain the swamp." I try to keep that in mind so I don't lose sight of my purpose to make good pots that are continually improving, with a certain freshness and spirit injected into them.