Zeplin - Collaboration app for UI designers & frontend developers
Invision - Prototyping and collaboration for design teams
Mightytext - Send & Receive SMS Text Messages from your computer. Sync'd with your Android #
Savahapp - The all-in-one design sharing, collaboration, workflow and app prototyping platform
ActiveWords - Auto correct on steroids
Pastel - Sticky note-based feedback collection tool for live websites