SmallDevTools - Handy developer tools with a delightful interface
Aeon Timeline - "The timeline tool for creative thinking. Capture, create and explore ideas."
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.
Preceden - Preceden makes it easy to build simple, powerful timelines
Profitable developer tools database - A database of 103+ hand-curated profitable developer tools
Timeline - Timeline is a cross-platform application for displaying and navigating events on a timeline.