Any NetBeans Platform application, not only NetBeans IDE, can benefit from the Darcula LAF for NetBeans IDE.

http://plugins.netbeans.org/plugin/62424/darcula-laf-for-netbeans

Here's the standard NetBeans Platform application that you get from the New Project wizard, with the plugin installed:

You'll find that the plugin also installs a tab in the Options window for configuring the LAF:

There are different strategies for installing the plugin into your application. E.g., you can include the plugin source code as a module in your sources or you can let your users install it as a plugin from your Update Center.