While I admire this guy's Moleskine-planner hack, my own notebooks (pocket, squared) end up a jumble of scribbles, notes, journal entries, diagrams of earring designs, places to eat, books to read, observations, websites to look up, stuff to accomplish in the next 90 minutes -- a veritable idea heap.
Each time I've tried using my notebook as a planner this rigid and organized, it's degraded into a flurry of random phrases, strikethrough'd tasks, and scribbles through Thursday's header to give Wedneday more space for an out-of-control to-do list.
But I guess you have to work with the system that works for you -- even if it's something as drab yet effective as the hipster PDA. That's why some people's desks feature piles (um...), while others are pristine.
What's the system you use for capturing brilliant ideas or to-dos? Is your system working for you?