Sortd - Rated the #1 App for Gmail
Clientflow - Project Management & Shared Inbox for Client Service teams
KanbanMail - A Kanban board for your emails.
Task Pigeon - Create, assign & manage your teams everyday tasks
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Client Portal - A client-friendly way to keep your projects organised