  Given a diagram of rings, one may consider the category of modules over them.
We are interested in the homotopy theory of categories of this type: given a
suitable diagram of model categories M(s) (as s runs through the diagram), we
consider the category of diagrams where the object X(s) at s comes from M(s).
We develop model structures on such categories of diagrams, and Quillen
adjunctions that relate categories based on different diagram shapes.
  Under certain conditions, cellularizations (or right Bousfield localizations)
of these adjunctions induce Quillen equivalences. As an application we show
that a cellularization of a category of modules over a diagram of ring spectra
(or differential graded rings) is Quillen equivalent to modules over the
associated inverse limit of the rings. Another application of the general
machinery here is given in work by the authors on algebraic models of rational
equivariant spectra. Some of this material originally appeared in the preprint
"An algebraic model for rational torus-equivariant stable homotopy theory",
arXiv:1101.2511, but has been generalized here.
