The 2009 public examinations (PSLE, N-Level, O-Level, A-Level) tentative schedule can be found here.
This contains a list of approved scientific and graphic calculators allowed for use in Singapore. This writeup contains images and user manuals of these calculators for quick reference.
The Singapore Examinations and Assessment Board (SEAB) was established on 2004 to develop and conduct national examinations in Singapore and to provide other examination and assessment services.
SEAB website contains the approved list of calculators, approved list of dictionaries, examination schedules for use in Singapore examinations.
In many secondary and JC school mathematics, the ability to graph mathematical functions are an important skill the student need to possess. These online graphing calculation is a good tool to use for explaining the behaviour of mathematical functions.
http://javaboutique.internet.com/graphcalc/
Math.com contains many fun and useful materials in picking up mathematics from primary school to secondary school levels.
Video/Audio resources on Fundamental of Physics offered by Yale Professor. Topics includes Newton's Law of motion, Kepler's Laws, Waves, Simple Harmonic Motion and many others. These are the topics covered in O and A levels physics.
http://science.pppst.com/ is a website offering free powerpoint materials on science topics. These powerpoints slides cover a significant amount of Physics topics taught at O levels and A levels.