Clearly, your maid of honor has many stunning qualities, otherwise you wouldn't love her so much. Unfortunately, organizational skills just aren't her strong suit.
If you're a note-taking, list-making maniac like me, seize this opportunity to bring her into the Type-A fold. Well, you can at least attempt to! Set regular meetings to discuss and divvy up tasks, confirm vendor appointments and share opinions. Provide her with a printed copy of her items if necessary. Sure, it might feel a little schoolmarmish, but the job has to get done, right? You can always downplay your micro-managing style with a light excuse or by poking fun at your own hyper-organized tendencies.
Be sure to keep your expectations in line with what you already know about her personality. It's unrealistic to expect too much detail or pit-bull tenacity from a free-spirited maid of honor. Instead of forcing her to tabulate RSVPs, you might try appealing to her creative senses by having her sketch floral arrangement possibilities or create a playlist for the D.J.