This thread is a few months old, but I thought I'd add my bit for the archives. I've been logging the settings of my shots for the last few months as I've been trying to learn more about film cameras and especially now that I have a Canon P, which doesn't have a built-in light meter. I had problems in the beginning with exposure and wasn't sure where I was going wrong. Making notes helped me to resolve most of my problems. It's nice to snap away without taking notes, but I'm finding that I can take better shots and do more when I take notes.
When I take notes, there is an unexpected benefit with regards to photographing people in public places. People close to me watch me for a moment out of curiosity, but quickly get bored. People a little further away from me don't pay attention to me as they normally would someone with a camera. By the time I take a meter reading (I use a Sekonic L358), write my note as to how I'm about to set the camera, shove my paper in my back pocket, put my pen between my teeth, and start focusing, they've forgotten I'm there. The quietness of the rangefinder shutter doesn't draw their attention--they're trained to hear the sound of an SLR mirror and shutter, though. Even if they look back to see if I took their picture, I'm busy making notes again. I don't think they know what I'm doing, but they aren't interested since I look more interested in what I'm writing.
More importantly for me, though, after getting over the initial bother and developing a rhythm to taking notes, it gets me more into the picture-taking zone. It calms me down and makes me think about what I'm doing. I'm less stressed about catching people in interesting circumstances. This results in me enjoying picture taking more than having taken pictures--or buying equipment.
Below is a copy of my notes for a recent roll of film, in case someone might find it useful. I've created this form in a spreadsheet on my computer and print a few copies to keep in my bag before going out to take pictures. It's half of an A4 (or letter-size) paper. That's an A5, I know, but I can't buy A5 paper here in Milan, so I cut an A4 in half after printing. On the other side are lines for shots 19 through 36. You'll notice if you look at it that my shutter is set the same for each shot. Lately, to deal with the madness of working without a TTL meter, I choose generally a shutter based on the 'sunny guide' (i.e., lighting conditions and film ASA). So, I really don't need to write down the shutter duration for each shot. I only need to record the aperture. Also unnecessary is a description of what I'm photographing. However, that helps me to make sure my notes are lined up properly with what I see on the contact sheet when the film is developed and printed.