Evil Car PC
Cross-platform (linux, freebsd, mac, windows, solaris, etc) C++ app utilizing Qt and an extensive plugin system. Utilizes a unique plugin communication system that allows plugins to communicate with each other without actually knowing about each other (via reflection (previously a java-only concept) and the Qt signals and slots framework). Also supports run-time remote configuration without the need to restart the application. This frontend is really defined by the plugins it uses rather than the frontend itself - could be anything from a simple 2D interface to a full-blown 3D interface with 3D rotating menus.
Currently in "release candidate" stages with a very basic plugin suite to demonstrate how the plugin architecture works and demonstrate plugin communication. Currently a source-only release. Requires Qt 4.x to compile. The cd-rom plugin requires SDL. The OSS mixer requires (gasp) OSS. Beyond that, no other libraries required.
The plugin interface is fully documented at this point in case there are any interested devs out there.