File-sharing

Astro File Manager - Free

https://play.google.com/store/apps/details?id=com.metago.astro&hl=en

Organization
Dropbox - Free

https://play.google.com/store/apps/details?id=com.dropbox.android&hl=en

Organization
Evernote - Free

https://itunes.apple.com/us/app/evernote/id281796108?mt=8

Organization
Explain Everything - $2.99

https://itunes.apple.com/us/app/explain-everything/id431493086?mt=8

Annotation
Genius Scan PDF Scanner - Free (Apple) or $6.99 (Android)

https://itunes.apple.com/us/app/genius-scan-pdf-scanner/id377672876?mt=8

Document Scanner
Notability - $4.99

https://itunes.apple.com/us/app/notability-take-notes-annotate/id360593530?mt=8

Organization
Popplet - $4.99

https://itunes.apple.com/us/app/popplet/id374151636?mt=8

Organization
SimpleMind+ - Free

https://itunes.apple.com/us/app/simplemind+-mind-mapping/id305727658?mt=8

Organization
Skitch - Free

https://itunes.apple.com/us/app/skitch/id490505997?mt=8

Collaboration
SoundNote - $4.99

https://itunes.apple.com/us/app/soundnote/id364789577?mt=8

Voice Recording