Android: Extensive Notes is not your average note-taking app. Just as its name hints, it does a bit more than its peers, and in this case that means a list of features 67 bullet-points long.
Not only does it take notes, but it takes notes in text, audio, video, QR codes, photos and drawings. Some even better features include creating to-do lists, adding events to Google Calendar, geotagging notes, sharing notes, and adding documents or other files as attachments to notes. That's only some of the things Extensive Notes can do, and the free version of the app can do all of it. The "Pro" version, priced at $1.98, adds customisation and settings features.
The almost comically long list of features in this app makes it less a simple note-taking app, and more a productivity tool for almost any occasion. It has a random password generator, a comprehensive unit converter, and built-in calculators for tipping, discounts, sales tax, BMI, Ohm's Law, Decibel change and more. It can look up words on the fly, add phone contacts as tasks, and it's got Google Translate built-in. There's even an "Artist Image" lookup, to help users add polish to their phone's music collection.
There are more features in this app, and the developer is almost constantly adding to the list as users make requests. Extensive Notes doesn't sync to an online service, but it allows the user to create on-the-fly backups of its database to the phone's SD card instead. The only real drawback for the app is that, with all its features, buttons in the UI are pretty small. Otherwise, the overall look of it is clean, and very well-done.
Extensive Notes [Android Market]