For a site with an extensive collection of Excel files for both GCSE and A level – see Mike Hadden’s MathsFiles site.
There are other resources also, including some for Autograph. Mike now has a blog where you can find out more about his Excel files for teaching (scroll down) and also learn more about macros – have a look at the Macro Recorder Demo.
A useful feature to help explore the Excel files is the option to see a screenshot.
These spreadsheets could be usefully used for demonstrations in the classroom and students could then study the examples further themselves.
The A Level files include resources for Statistics and Mechanics as well as Pure Mathematics.
The Statistics resources include a Normal trainer with the option to study ‘backwards’ problems and a very clear contingency table calculator.