Language integration is an important issue in the area of software maintenance and reengineering. We describe a novel solution in this area: automatically applied and composed split objects. Split objects provide a language integration that goes beyond simple wrappers by integrating object identity, state, methods, and class hierarchies of entities in two languages to one logical entity. The split object concept can be applied as an aspect-oriented solution, in which an aspect of a system is implemented in another language. After describing these concepts and two split object frameworks that we have implemented, we discuss how split objects can be applied for other maintenance and reengineering tasks than language integration. These application fields include software component testing, dynamic feature analysis, and variation and configuration management.