Sortd - Rated the #1 App for Gmail
Gmail Tabs by cloudHQ - No more scrolling for Gmail Labels by alphabetical order
KanbanMail - A Kanban board for your emails.
Asana for Gmail - Turn emails into tasks without leaving your Gmail inbox
Airmail - Airmail is a lightweight and lightning fast mail client for Mac.
Drag for Gmail - Transform Gmail into organized To Do lists (like Trello)