Crmble - Easy peasy crm for Trello
Elegantt for Trello - The most elegant way to manage your Trello projects
Onesheet CRM - The Simple CRM for Google Sheets
Hello Epics for Trello - Simplify your Trello board with parent/child relationships
SquareOne - Email. Stress-free.
TunnelVision - See your next Trello tasks every time you open a browser tab