Here's another vote for zip lock bags and Tupperware bowls.  I like to use the zip lock bags for nuts and bolts, small pieces, etc.  I keep everything separate and label them as I go.  The Tupperware bowls are good for small to medium size parts, plus you can put the zip lock bag with the bolts into the Tupperware.  I then put all the bags and bowls together in some sort of a storage box.  For something complicated, I put drawings, pictures, diagrams together with the various sub-assemblies.  Makes things much easier when it's time to put things back together, especially if there's been some time gone by.  The other thing I do is to laminate any diagrams, drawings, pictures, etc., in clear plastic.  Then, when I'm working on the car, I can keep the diagram right there with me and not worry about it getting trashed.