Rails: reusing models, controllers, and even views between Rails applications

I have a rails application that contains some fairly general functions (e.g. user management). I would like to use this common functionality in other rails applications without copying it. The tough part seems to be that this code contains several models, controllers, and views.

I know that gems and plugins allow you to use the code, but they seem to be more suitable for sharing the utility and library functions, rather than with the main parts of the application.

Any advice on how to do this would be greatly appreciated.