For many of us, pen and paper are our preferred tools to capture our thoughts, set goals and remember tasks. If that describes you, you'll probably love this index card organising system.
Called the "Pile of Index Cards" or PoIC, the system combines both GTD task organising principles and information capturing. Hawk Sugano, a.k.a. hawkexpress on Flickr, describes his methodology in detail on Flickr, an Unclutterer has a nice overview of it as well.
Basically, you just need index cards and a storage box (a "Dock") with tabs. Sugano uses four types of cards in this system: a record card for a diary and other records of the day, a discover card for a brain dump, a GTD card for next actions, and a cite card to record other people's ideas, such as quotes from a book or other sources.
He marks the top of each card so he can easily identify it when it's in the dock, as well as tabs for organisation.
A Moleskine notebook with pockets allows him to take his index card inbox with him wherever he goes.
It's an old-fashioned solution, but it's simple, cheap and efficient.