Flow-e is a visualization layer on top of your Gmail or Outlook inbox. It provides an elegant Kanban-like workflow that's combined with the ideas behind Inbox Zero and GTD. Flow-e eliminates the need of external task management tools and transforms your inbox into a central To Do app.
Sortd - Rated the #1 App for Gmail
KanbanMail - A Kanban board for your emails.
Drag for Gmail - Transform Gmail into organized To Do lists (like Trello)
Get My Receipts by cloudHQ - Organize your receipts in one click
OneBox.io - Sync e-mail attachments to GDrive, Dropbox, Box, or OneDrive
KanbanFlow - KanbanFlow is a Lean project management tool allowing real-time collaboration between team members. Supports the Pomodoro technique for time tracking.