RafflePress - RafflePress is the best WordPress contest and giveaway plugin. Grow your email list, followers, and website traffic with viral giveaways in WordPress.
Jira - The #1 software development tool used by agile teams. Jira Software is built for every member of your software team to plan, track, and release great software.
UpViral - Referral marketing platform enables anyone in running effective and profitable viral marketing campaigns – in minutes.
Basecamp - A simple and elegant project management system.
Tremendous - Tremendous is a customer and employee loyalty platform that allows companies to reward their customers for surveys promotions and referrals.
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.