Toggl - Toggl is an online time tracking tool. It features 1-click time tracking and helps you see where your time goes. Free and paid versions are available.
Floating Prompt - Invite your users to support your launch anywhere
Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.
Friend Hunt - Get desktop notifications when your friends comment on PH
RescueTime - Time management software that shows you how you spend your time & provides tools to help you be more productive.
History of Product Hunt - Learn community building from Product Hunt's example