The Clay Database Modelling tool would be nice for assisting with the Schema development & generation. The only missing component to Clay is that it currently only supports a few/ open source RDBMS products. In order to be used for many production projects, Oracle and IBM would need to be supported (and in that order based upon market share).
In addition to database modelling, or in leu of database modelling, supporting an O/R mapping tool would be great. I would say that supporting JDO would be ideal, but my personal feeling is that JDO 1.0 is not ready for mainstream usage and that you would need to wait until JDO 2.0. Hibernate, Jakarta Turbine, Jakarta OJB, and Toplink (owned now by Oracle) appear to support most of the capabilities that people need for developing large enterprise applications. Ideally, the integration with one of these products would include a graphical mapper that would generate the mapping file syntax (typically an XML file) for mapping between the java class and the database table.