Sitemod - Modify any website in real-time. Share it with the world.
SmallDevTools - Handy developer tools with a delightful interface
VisualSitemaps - Autogenerate visual sitemaps in seconds.
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.
Transformicons - Animated icons, symbols and buttons using SVG and CSS
Profitable developer tools database - A database of 103+ hand-curated profitable developer tools