The Portable Extensible Toolkit for Scientific (c)omputation [PETSc] is in their own words, "a suite of data structures and routines for the scalable (parallel) solution of scientific applications modeled by partial differential equations". In PetscExt, we provide support for additional implementations of Vec, Mat, KSP, PC and SNES. One of the main features of PetscExt is the types which allow block objects to be defined. A block objects may consist of a vector, matrix or preconditoner. We provide block types for Vec, Mat & PC, which together allow us to explore different solution strategies for coupled systems of p.d.e's, whilst at the same time inherting all of the flexibility provided by PETSc.