SpringpadDigital notebook service Springpad has doubled its total registered users in the last six months to 2 million, the company tells VentureBeat.

Springpad’s mobile apps let you save information about movies, wine, books, check-ins, recipes and more that you come across during the day. It then organizes that data within smart notebooks and arranges it into useful packages. For example, if I’m looking for movies in the area, I can pull up a list of the most popular movies among my friends. That movie page will have a map of theaters in the area, movie times, etc. It’s a pretty useful tool for keeping track of things and discovering your next few steps throughout the day.

Apparently, I’m not the only one who thinks so. Springpad’s user base has saved over 27 million things using the service, according to the company.

“People’s habits are shifting from sharing their activities with one large network to smaller subsets of friends, like Facebook’s smart friend lists and Google’s Circles,” said Springpad CEO Jeff Janer in an interview. “What Springpad does is take the data from what you and your friends share and turn it into something much more useful.”

Right now, the company makes its money through affiliate partnerships from new business it directs to various products and services. Its mobile apps send users alerts for relevant news, price drops, product availability, coupons and other retail offers, which help facilitate that part of the business. Eventually, Springpad plans to open up relevant advertising into its smart notebooks while continuing to keep the service free for consumers.

Founded in 2008, the Boston-based company has $5 million total funding to date. Springpad faces competition from services like Evernote.