As this thread currently has a lot of critics, I just want to put in a personal plug for JD. I've been using it for some time now for family and personal data and it has been enormously helpful. It's true that it is occasionally vexing to have to choose one category for a given thing, but (a) it's usually not, (b) it's ok to reorganize categories, (c) I have found that often if there's something important that fits equally well in more than one category, (c1) either I need to refactor my categories, or (c2) it's probably going to be ok if I just pick one and allow myself to recategorize later. This almost never happens anyway.
And in the mean time, all my stuff is searchable, browsable, findable, and tidy.
I'm not saying it will work equally well in all environments or for all purposes, but for mine, it solved many years' worth of stress.