Pennywise - Cross-platform application to open any website or media in a floating window
Hologram - Frontend Development and Design
PiP for Mac - Always on top window preview similar to the popular windows only OnTopReplica
CleanMyMac X - Clean, protect and speed up your Mac
PiPer - A DIY Minecraft computer to build gadgets
ScreenPlay - Open-source and cross-platform Wallpaper, Widgets and AppDrawer app.