Apps for Digital Note-Taking - NYTimes.com Years before Steve Jobs introduced the iPad to the world, tablet computers made regular appearances in science fiction shows. Fans of "Star Trek" will remember ensigns tapping on digital tablets or asking an officer to scribble a signature on one. Lots of those fictional machines had one thing in common: they worked with some sort of stylus and were digital equivalents of a traditional notepad. The similarity to writing on paper is enhanced in the Papyrus Natural Note Taking app by a feature that makes thicker or thinner lines depending on how hard you push the stylus on the screen - and no electronic stylus is necessary. With the Noteshelf app, you can choose from many predefined types of digital paper, including plain and ruled pages, and even one designed for musical notation. ePaper departs from the idea of simulating the notepad you would use in classes or meetings. Many of today's most popular tablets are finger-friendly, of course. But for a host of note-taking apps, the devices, like their fictional cousins, work best when paired with a stylus. My favorite of these stylus-friendly options is Noteshelf, a $6 iPad app by Ramki. Its main interface is an empty page ready for you to write on, with controls in an icon bar at the top of the screen. You can choose from many predefined types of digital paper, including plain and ruled pages, and even one designed for musical notation. Noteshelf supports digital styluses that connect to the app and relay information, like how hard you're pressing on the screen, to produce light or heavy lines. But the app also works well with a basic stylus, and you can get similar results with some easy tricks - move the stylus faster to get a thinner line, for example. Hand-writing notes feels a lot like writing with a pen and paper. A highlighter pen and eraser options are also slick, and there is a great system for selecting lines, drawings or text so you can adjust them later. There is even an emoticon option - a feature students may appreciate to cheer up boring class notes. You can add photos to your note pages, using intuitive multitouch gestures to move and resize images. But switching from a stylus to finger controls is a little jarring. Noteshelf is good at ignoring the touch of your wrist if you accidentally lean your hand on the touch screen while writing. Your finished notes can be shared as images over e-mail, Twitter or Facebook, or sent as PDF files. On Android, a rough equivalent is Papyrus Natural Note Taking, which is free. Visually, the app is a lot like Noteshelf, with a page of simulated paper to write on and a slim menu bar at the top. It also has many of the same features. The similarity to writing on paper is enhanced by a feature that makes thicker or thinner lines depending on how hard you push the stylus on the screen - and no electronic stylus is necessary. The app has different paper backgrounds, and you can add images. Adding typed text to your handwritten notes or drawing geometric shapes requires an in-app purchase. Because of all the different versions of Android and the multitude of devices that run it, interacting with the menus in this app may require a little more effort than you expected, but they still work well. On iOS, the $2 app ePaper by Effectmatrix is a more open design and departs from the idea of simulating the notepad you would use in classes or meetings. It also has tools that let you sketch and paint onto your note pages. A broad array of pen, pencil and brush-emulating tools are included in the basic price; a pack of additional paper designs costs $1. EPaper's menu system can take some getting used to; to get access to options, you "scroll" the on-screen icons with a swipe of your stylus in a slightly unexpected way. But over all, it's easy to use, and if your notes tend to be artistic and free-form, this may be a good app for you. On Android, the free Write by Stylus Labs is a simpler offering, with fewer pen types and digital paper designs. But it's still powerful, and you can export notes as images or PDFs via a variety of services like e-mail or Dropbox. It can also support electronic styluses. Relaxed note-takers will appreciate not having to worry about moving to a new page when you've filled one: the pages automatically scroll up to expose more blank space when you approach the bottom edge. Penultimate (free on iOS) and FreeNote, note everything (free, or $6 for all features on Android) are also notable choices. Taking handwritten notes, even on a digital tablet, is much more personal than typing in a word processor, so it's worth trying some alternatives to find the one you like. Hundreds, a hit puzzle game on iOS, has arrived on Google Play for Android devices for $3.14 (on sale; ordinarily it's $5), It's deceptively simple and very addictive. ... AT&T Locker, a cloud storage service for AT&T customers previously available on iOS and Android, is now available on Windows Phone 8 smartphones. The app is free.