Ruby on Rails User Management Engine/Framework? (with web pages)

Hi,

There are quite a few post/recommendations re Rails authorization plugins. What I'm asking here however is whether there is a popular/good Ruby on Rails Engine (or framework) that includes the user interface pages as well (and controllers/models etc). So something one could integrate in (Engine) or use as a starting point that includes:

- sign up (e.g. user creates a login, then email is sent with activation link) - authentication - authorization - User interface allowing user to:   - change password - Delegated Administration (Optional)   - supports multiple/separate companies/groups using the same application   - Admin User for Company/Group X, and allocate access to Person Y (create a new user)   - UI to allow user to perform these functions

I threw in the last delegated administration as an optional extra. If there a good/populate product that doesn't have this I'd rather hear about it.

Thanks in advance