Do I dare suggest an improvement to the already perfect Hipster PDA?
3 x 5 cards can be, let's face it, bulky. How often do users of the excellent Hipster actually write from top to bottom and side to side of each and every 3 x 5 card?
Try this: Find a guillotine and cut some 3 x 5 cards in half, making twice as many 2 1/2 x 3 cards. Clip them together with a little binder clip. Secrete them somewhere on your person, and use them as you would a full-sized Hipster.
Twice the number of (already cheap) cards, half the size, half the expense, half the required space.
Works for me.