A little invoicing application developed writing only 4 simple Java classes: Customer, Invoice, InvoiceDetail and Product.
A project management tool for software products, with versions, per-employee plans, clients, etc. It is the official issue tracker for OpenXava.
This OpenXava demo has user login, hierarchical menu, multitenancy, users and roles management, and advanced security. It uses XavaPro.
This is an example of a mobile web application with OpenXava. You don't needed to write any code to have a mobile user interface, just point your mobile browser to your application. This demo uses XavaPro.