BandNext - Discover bands that sound similar to artists you already love with BandNext. A single click saves your results to a Youtube playlist.
Grammarly - Clear, effective, mistake-free writing everywhere you type.
Musicroamer - A visual Pandora for discovering new music
LanguageTool - Free proofreading tool for OpenOffice, LibreOffice, Firefox, and Chrome.
Music Walker - Explore and play (via YouTube) songs similar to a seed song.
Editsaurus - Highlights potential pitfalls in your writing to encourage good habits.