The Luminous Landscape is a great web site with a lot of information on digital photography, excellent photos and nice reviews of related hardware and software.
I singled out a nice little article about what they call “the colour gremlins” (More commonly, this is known as digital sensor noise). What is interesting is that they present a nice simple way to reduce this problem in a way that allows to clean up the digital image of the noise artefacts (little coloured spots seen in high ISO images).
The technique is quite easy to handle. However, it is still better to avoid this situation and to use a low sensitivity (with less noise) or a better sensor (usually it means using a larger sensor like the ones found in Digital Single Lens Reflex or D-SLR).