The Fridge and Deep Freeze are the places you store ready and long-term reference. The Fridge contains things that deal with currently active projects. In terms of paper, it is usually a file drawer with file folders labeled for each project. The Deep Freeze is where you keep reference materials on non-active stuff - usually another file folder. In electronic terms, Evernote is an awesome (and free) way to hold onto both your active and non-active reference. On the Mac, Yojimbo is another popular product.
I have two file drawers, one as a Fridge and a much larger one for my Deep Freeze. These days, I'm much more paperless, as I invested in a Fujitsu scanner which I use in combination with Evernote. If you do not use Evernote, I really can't stress how awesome it is in implementing File and Forget. It also integrates with several Master Planners.