While I was checking out the "Getting things Done" entry on Wikipedia I came across a great method for a PDA called the Hipster PDA. Its kind of a tongue in cheek - back to basics version made out of index cards, and a binder clip. What I might call "redneck/ghetto style", if I might be so bold as to flit of the edge of offensiveness. ;-) With the addition of a couple of Papermate pens you'd be all set!
Photo by John Arundel, September 2005, Wikipedia.