Kashoo - Kashoo mobile and online accounting software for small business. Cloud based system for invoicing, expense tracking & bookkeeping. Free Trial.
Sortd - Rated the #1 App for Gmail
Akaunting - Free, open source and online accounting software for small businesses and freelancers
KanbanMail - A Kanban board for your emails.
FreshBooks - The ideal accounting software for small business owners.
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.