Static type checking is a thoroughly proven method for identifying errors in programs and sophisticated type systems such as the Aspinall/Hofmann system catch even more errors but how can we go further still? Extended static checking is an innovative and productive new program analysis technology which uses a limited amount of automatic theorem proving. As the name implies, extended static checking finds faults in programs which are not caught by conventional methods of type checking and static analysis as implemented in programming language compilers. In the way that we are using this technology to meet the demands of e-Science application development the main class of fault that we will catch is failure by exceeding a resource bound but other programmer errors are found by this approach also. Extended static checking is a ``lightweight formal method'' which requires much less effort than full formal program verification.