This is an idea I cooked up a while ago, which the cap thread just reminded me of.
It's based on the system that Vegas casinos use to track not just their gambling club members. (slot clubs, etc.) The basic idea is to create a system that not only rewards APs (and heck, other guests!) for their purchasing behavior, but also tracks it for marketing purposes. For every dollar amount you spend, you get x number of points. For psychological reasons it's best if these numbers are not directly equivalent (eg: people don't look at x points and think x dollars, even though it is). Anyway, they build up points and can redeem them for either merch, or meals, etc, just like you would do in a Vegas casino.
Now, this WOULD entail a significant investment in reprogramming the cash registers to read these cards and have that plug into the card system, but it would allow Disneyland to see who's spending what and where. Just like Vegas casinos, if Disney sees that some guests are spending $5000/yr and others are spending $200, they can tailor different special offers to each of those groups.
For example, my boyfriend (we'll call him Gaucho), and I spend a lot of time in Vegas. He gambles more than I do (that is, wagers more money AND spends more time, as I run out faster - being poorer). Obviously Vegas would like both of us as customers, but the hotels want HIM more than they want ME. Reasonable under the circumstances. So, every now and again one of the hotels will send out room rate offers to their club members. I get a postcard offering $59 weeknight, $89/weekend room rates at some great hotel (they are pretty decent discounts), and a few days later, he'll get one from the same hotel, offering $59 weekends and free weeknights.
Under a similar system, people who spend thousands at DL might be sent a great room rate at a Florida hotel in order to encourage them to visit, knowing they'll likely be "making the most" of the trip with lots of dining and merchandise purchases. An AP who spends only a little might be sent a slightly less good, but still decent, room rate offer locally. Or possibly a gift-with-purchase offer, like a pin for spending over $50 at Disneyana or maybe free appetizer at Blue Bayou.
Along with the tailored marketing, these people would be racking up points. Let's say for a moment that every dollar spent did earn one point. And perhaps an AP who racked up 600 points in one year could redeem them for the cost of a new AP, since they've shown that to make fiscal sense (eg: that they'll spend the dough once in the Resort).
This also allows Disney to come up with special promotions. Let's say there's some product they have a high margin on (is there any they don't?), like PINS. Perhaps they want to boost attendance during slow periods, or at least guest spending, so they offer double points on pin purchases on weekdays, or double points on desserts at the park restaurants. Use the point system both to reward spending, and to increase it by encouraging people to buy stuff they normally don't.