This week, I stumbled upon a new idea: character summaries. It's a simply concept. You mark down the pages that a particular character appears in, and write a few sentences on what goes on with that character from point to point in the story. Doing this is especially helpful for long projects, saving time that you'd otherwise spend sifting through dozens or even hundreds of pages of material.
Don't worry about going into heavy detail or motivations. You know what drives your characters. If there is a change in motivation, a brief sentence on that change will do. If a side character appears that you think might become important later on, make a note of that in the relevant annotation.
Just keep in mind that it's not a synopsis that you're writing, so you don't need to go crazy on the amount of information you record. If a few months go by between vignettes for a character, chances are that he or she will have forgotten some of the finer details of that last scene. Unless, of course, that character has a photographic memory.
Even then, photographic memory or not, you as a writer will want only the bare essentials of each scene. The summaries have less to do with character development and more to do with how the plot flows. For example, you don't want to have the first vignette take the character down one road to a particular goal, forget about that goal a hundred pages later and then have him or her go down another path that doesn't logically connect with the first one.