NW.js!

If you can build a website, you can build a desktop app. Electron is a framework for creating native applications with web technologies like JavaScript, HTML, and CSS. It takes care of the hard parts so you can focus on the core of your application.

Appcelerator Titanium, offered for free by Appcelerator, lets web developers use web technologies, open source and cloud computing to build native apps for iPhone, Android, Windows, Mac OSX and Linux.

WebDGap allows you to convert any website or HTML/CSS/JavaScript web application to a native Windows, Mac, Linux, and Chrome application.

Rapid Application Development tools for native Android, iOS and desktop applications. The simple way to quickly program real world apps. Programming language similar to Visual Basic.

Convertigo is the most advanced Open Source Mobile Application Development Platform for Enterprises, featuring all the required components needed to develop and to run cross-platform mobile enterprises application connected to enterprise's back-end business applications.

Cappuccino is a framework which makes it easy to create advanced web apps. With just a few lines of code you can have an app built with full undo and redo, truly amazing table views, drag and drop and every modern UI appearance and behaviour you might expect on the desktop.

Mobile App Development Platform for non-developers: create native apps; send to devices or submit to app stores; manage apps from a secure CMS.

With the Magentrix Social Intranet, enable your employees to increase productivity and work smarter in a secure, easy-to-use, and mobile-friendly environment.