I'm not getting paid for any of these recommendations (I wish they would!), but these are the best tools I use with and without students in my classroom.
Symbaloo--My Symbaloo says a lot about the websites I use, and it's updated constantly. Of course, these are web-based, but some also come as apps in the iTunes, Google Play, and Chrome Web store. I use all of these with my students.
Chromebook apps in addition to the ones listed above:
Google Keep (available in iTunes & Android stores)
The QR Code Generator
Pixton for Google Chromebooks
YouTube Capture App
Prezi (available on web)
Thinglink (available in iTunes & Android stores & web)
GradeCam (available in iTunes & Android stores & web)<--ASSESSMENT HEAVEN!!
iPromptPro--a teleprompter for speeches
Kindle (available in iTunes & Android stores & web)
Booksource Classroom--my entire classroom library is digital & sends reminders when books are due!
Gaffclass' MUST HAVE Chrome Extensions: (I use them daily!)
Send to Google Classroom
Save to Google Drive
The QR Code Extension
Goo.gl URL Shortener