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.
SendOut - Affordable email marketing for bloggers and influencers
hiTask - HiTask is a free shared task list for your team. The place to plan, organize, and stay in sync.
Mailzak - Give a boost to your #EmailMarketing
Mail Pilot - Beautiful task oriented email client for Mac, iPhone, & iPad
Mailblast - Email marketing on a budget using Amazon SES