Vocabulary Miner - Flashcard app with offline learning, spaced repetition, no ads, export & import, statistics...

LanguageTool - Free proofreading tool for OpenOffice, LibreOffice, Firefox, and Chrome.

Anki - Anki is a program which makes remembering things easy. Because it's a lot more efficient than traditional study methods, you can either greatly decrease your time spent studying, or greatly increase the amount you learn.

Grammarly - Clear, effective, mistake-free writing everywhere you type.

Teach2000 - A private teacher to help you memorize a foreign language, topography or even the history of Italy...

Editsaurus - Highlights potential pitfalls in your writing to encourage good habits.