SmallDevTools - Handy developer tools with a delightful interface
PiPer - A DIY Minecraft computer to build gadgets
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.
Helium - Helium lets you accept payments by credit card for anything you want to sell online.
Profitable developer tools database - A database of 103+ hand-curated profitable developer tools
PiP for Mac - Always on top window preview similar to the popular windows only OnTopReplica