wxWidgets - wxWidgets: Cross-Platform GUI Library
Fluid - Turn Your Favorite Web Apps into Real Mac Apps.
Electron - Build cross platform desktop apps with web technologies
WebCatalog - Run your favorite web apps natively
GTK - GTK+ is a multi-platform toolkit for creating graphical user interfaces.
Web2Desk - Web2Desk is a tool to convert your favorite websites to Desktop app in just one click.