Cold Turkey - Cold Turkey is a free productivity program that you can use to temporarily block distractions so that you can get your work done!
TopTracker - Beautiful, free time tracking
Time Sink - Time Sink helps you track how you spend your time on your Mac.
timeBuzzer - timeBuzzer enables freelancers and project-driven teams to track their time at the touch of a button, understand where their time goes and create reports with just a few clicks.
Anti-Social - Anti-Social is a productivity application for Macs that turns off the social parts of the internet.
Cattr - Cattr is a free open-source self-hosted time tracker with desktop clients for windows, mac, linux.