With 50 million users, Evernote is the pack's leader. The service, available on iOS and Android, has most everything users need like the ability to organize information into individual notebooks and share with others. To avoid having to type notes, Android users can use an automated transcription service that turns speech into text -- at least in theory. However, there is no built-in equivalent for iOS users. Evernote's free service limits uploads to 60 MB per month. A premium version with up to 1 GB of uploads per month costs $45 annually. Earlier this month, Evernote suffered a black eye when it revealed that hackers had infiltrated its computer system. As a result, it had to reset all user passwords.
Seven tales of competition that changed business forever. Available free to subscribers on Fortune's tablet apps.