Listaller is a distro-agnostic 3rd-party application installer with close integration into PackageKit.  The project uses GPG-signed installation packages, which can be installed for all users (as root) or only for one user without needing superuser-rights.  Dependencies are resolved automatically using PackageKit. Listaller applications can be installed and removed using any PackageKit frontend available, without needing extra tools, however some specialized UIs are available and integrated with existing package-management tools.