A co-founder of Adaptive Path, Peter Merholz is a fantastic active mind. He reads widely, and fortunately for us, he applies much of what he reads to information architecture. His site, PeterMe has long been a nourishing place to study the unconscious principles of organization in our daily lives.

He sent a short answer on his scheme for Personal Filing:

Right now, I organize everything in iCal.

Mostly using ToDos (right hand side). I try to put in there every little thing. And I use it to store writing ideas ("write up keynote presentation", "drawing of overlapping disciplines"), etc. etc.

And a picture: