One customer of London-based fashion platform Lyst has more than 100,000 items on her wish list, all collected during the last year. She may be an extreme case, but the aspirational teenager from South East Asia is not alone in using wish listing as a form of entertainment.

A Future Foundation survey found that 26% of consumers think of wish listing as a valuable activity in its own right – a figure that rises to 56% in China and 59% in Indonesia.

Will Seymour, brand officer at Future Foundation, a London-based company that studies consumer trends and insights, said, "Wish listing has become a key pre-purchase behavior for many consumers. It's a new type of retail behavior – it's not shopping, it's leisure."

In many ways, wish listing is the 2015 version of cutting pictures out of magazines and saving them in folders for inspiration. The big difference is that wish lists are digital and shareable online – a space where marketers can easily connect with potential customers.

Simon Hathaway, global chief retail officer at the Cheil Network, said, "Access to a wish list is a fantastic opportunity. It gives you live data about purchase intent and preferences, and allows you to use dynamic pricing to build up a relationship."

Many Lyst customers pile up wish lists, especially at this time of year. Chris Morton, Lyst's founder and CEO, said, "It's one of the behaviors we were excited about from the beginning – hence our name. People love fashion. It's entertainment. Wish lists are a way to interact with it, and people will usually pull the trigger [to make a purchase] every now and then. Customers might save items until they get a paycheck or a bonus, or at this time of year, people put items in their wish lists so that when Black Friday hits, they know we'll contact them immediately if the item goes on sale."

Marketers are wising up to the wish listing phenomenon and finding ways to tap directly into the behavior.

Wal Mart's Christmas campaign includes a spot where a man sings, "Have Yourself a Merry Little Wish List," while Argos in the U.K. has created the "My Christmas Wish List" app, which kids can download and use as a hotline to Santa – eliminating the need for laborious handwritten notes.

EasyJet airline has recently introduced the Book-It List, where travelers are encouraged to fantasize about future holidays and collect their bucket list destinations in one place.

Michael Lee, the executive planning director of EasyJet's agency, VCCP, said, "We're not inventing behavior; it's something people already do. We are just pushing open the door, finding new ways to inspire people, and giving them a straightforward user experience."

Mr. Lee added, "Travel is a good category for this, along with gifts, furniture and fashion, because people do spend time thinking about these things."

Pinterest, of course, is the home of the wish list, and this year introduced buyable pins in a bid to commercialize the site. Amazon has an established community around public wish listing, and recently integrated booksharing site Goodreads into Kindle.

New businesses are springing up to cater to wish listing behavior. One app, Wisher, started last year by former London agency exec Maz Cohen, has gone a step further and created a universal wish list. Users can add items by taking photos, scanning barcodes, or via online browsing. Once a friend has bought a present for you through Wisher, the item/wish is anonymously marked "granted."

Developments like these allow consumers to introduce new stages into an increasingly complex online shopping process. Mr. Hathaway said, "The traditional path to purchase is almost dead. It's now a much more chaotic mix of searching, sharing and shopping, but the wish list – because it's the point at which you share, even if only with the retailer -- is smack in the heart of it."