SEAT YOURSELF is a rails app designed to allow users to make better reservations online.
The app involved four models - restaurant, reservation, user, superuser - and used a variety of RESTful and MVC principles to be operational.
The challenges with an application like this lie in validation (i.e. having so many input fields that can be broken by a user) and problem solving initiative on behalf of the restaurant owners (to deal with issues like booking frequency, acceptable booking hours, restaurant capacity, etc ++++).
If you have any questions, message me!