Having taught for many years in two different schools the best revision materials that I have come across are the following:

1. CGP Materials

The best by far. CPG offer a wide range of materials which are "immaculately presented and marvellously funny". Great value for money.

http://www.cgpbooks.co.uk/pages/books_gcse_maths.asp

2. Bitesize

This is a great interactive website that makes learning fun.

http://www.bbc.co.uk/schools/gcsebitesize/maths/

3. Revison Cards

Great to break up a topic into small chunks.