One of my players takes detailed notes of each session, so I've become lazy in that I rely on her to remind all of us who the players met, how much treasure they have, and what trouble they got themselves into.
I have extensive files on my desktop computer, and generally I organize them like this: For each area the PCs are spending at least a game session in, I have a folder. All the NPCs, maps, plot hooks, random encounters, adventures and handouts that apply to that location go in the folder. I usually color code all the related documents, so for instance all materials from the Village of Sandpoint would have their titles and section headings in blue. Once the pages are printed out this color coding allows me to quickly see which pages go together if things get separated.
I use a 3-ring notebook at the table, which contains the entire contents of the folder for the area the PCs are currently in, as well as the party character sheets, some background information on the campaign world, character creation guidelines and house rules, and usually some pages from previous sessions that still apply somehow (NPCs with continuing stories, ongoing plotlines and so on). All told, the binder will have around 40 pages in it for any given session.
My system is not perfect, but until we spring for a decent laptop (our current one is a wheezing old dog) I don't see myself giving up paper at the table.