DataNucleus AccessPlatform is a standards-compliant Java persistence product. It is fully compliant with the JDO1, JDO2, JDO2.1, JDO2.2, JDO3, JPA1, and JPA2 Java standards, and provides a REST API. It complies with the OGC Simple Feature Spec for persistence of geospatial Java types. It allows access to all popular RDBMS available today, together with the MongoDB, LDAP, NeoDatis, JSON, Excel/ODF spreadsheets, XML, BigTable, HBase, and Neo4j databases.
Querydsl is a framework that enables the construction of statically typed SQL-like queries. Instead of writing queries as inline strings or externalizing them into XML files, they can be constructed via a fluentDSL/API like Querydsl. It supports JPA, JDO, Java Collections, SQL via JDBC, Lucene, and Hibernate Search.
Automated Business Logic (ABL) is a transaction logic engine. You define the behavior of your persistent objects declaratively, and the engine will take care of executing and enforcing your logic at commit time. Despite its simplicity, this approach is remarkably powerful, and can replace a large portion of the code in most transactional applications that use Hibernate.
The Generic Repository (grepo) is a framework for Java which allows you to access (database) repositories in a generic and consistent manner. Using grepo, it is generally no longer required to provide all the boilerplate code which is necessary in order to access (database) repositories from Java. All you have to do is write appropriate database code (queries, procedures, functions, etc.), an appropriately annotated Java interface, and very little Spring configuration.
SlimWeb aims to replace Struts or JSF in your J2EE application, but is closer to Rails or TurboGears in its heavy use of convention-over-configuration, simplicity, and power. It aims to reduce (and most of the time completely eliminate) all boilerplate code, XML configuration files, and even deployment times.