Apps to Skinnable

Kantaris Media Player is an all-in-one multimedia solution designed to deliver a seamless playback experience. It supports a wide range of audio and video formats, offers advanced features like subtitle support, Last.fm integration, and extensibility through plugins, aiming to be your go-to player for all media needs. Its focus on being lightweight and ad-free enhances its appeal.

MPlayer OSX Extended is a lightweight and versatile video player for macOS, built upon the robust MPlayer engine. It offers excellent format compatibility, subtitle support, and a clean interface for a focused playback experience.

Nightingale is a highly customizable cross-platform audio player with a focus on extensibility, featuring a beautiful interface, a wide array of supported formats, and tools like media library management, podcast playback, and integrated web browsing.

SPlayer is a lightweight media player known for its focus on high-quality video playback and integrated features. Despite being discontinued, it offers a portable solution for playing various video and audio formats, including HD and 4K content, with support for automatic subtitle downloads and image enhancements.

Audacious is a highly customizable, lightweight audio player designed for discerning listeners who prioritize sound quality and system resource efficiency. Supporting a vast array of audio formats and extensible via a robust plugin system, it offers a classic, skinnable interface for a personalized listening experience.

Rainmeter is a free and open-source desktop customization application for Windows. It allows users to display various types of information, such as system metrics, time, weather, and RSS feeds, directly on their desktop through highly customizable 'skins'. It's a popular tool for creating personalized and functional desktop interfaces.

Launchy is a discontinued yet highly efficient open-source keystroke application launcher for Windows, macOS, and Linux. It allows users to quickly open programs, documents, and perform searches by typing their names, significantly speeding up workflow.