Yes, there were many model coupling projects in the past, as well as many ongoing coupling projects in the present and near future.
The main motivation behind model coupling is the need for the interactive feedback processes between two or more separate physical systems, for example, atmosphere and ocean. Historically, these models have been developed independently of each other, i.e. they were uncoupled - unaware of each other. Given past and current technology and knowledge, modifying the models' source code so that they can exchange information in a consistent manner was a much smaller effort (typically few years) than it would take to develop a unified system model from scratch (i.e. atmosphere-ocean as a single dynamical core). Another advantage to the coupling approach is that different physical systems often describe processes that operate on very different spatial and time scales. Thus, it is often computationally advantageous to let physical systems have distinct models that are "coupled" through an intermediate layer.
The vast number of coupling projects throughout the 1990s and 2000s have demonstrated the need for more standardized coupling libraries or frameworks that would cut down on duplication of effort, software bugs and development time. @BHF's answer mentions a few of those. Probably the most mature and feature-rich framework at this point is the Earth System Modeling Framework (ESMF). ESMF provides data abstraction for geophysical models, field regridding, parallel computation capabilities and many others. ESMF provides Fortran, C and Python (limited) APIs. Many atmosphere, wave, ocean, land and sea-ice models are now ESMF-compliant, so coupling of these models is more feasible than ever.
Indeed, there are also efforts toward a standard and software design convention that would facilitate model development and coupling. Such standard is the NUOPC layer and is supported by the ESMF library. NUOPC sets the guidelines for software design and field naming conventions that promotes model interoperability. Any models following the NUOPC design conventions will be interoperable with each other out of the box, so the burdain is now moved to the actual model developers to make sure that their packages follow the new standards.
(My PhD thesis in progress uses ESMF to develop a coupled atmosphere-wave-ocean-model.)