For my Blackook I use the disposable wipes that is normally used to clean glasses to clean my screen and trackpad. You should be able to get them at your local supermarket or optician. They are dirt cheap. Should be like 3 euroes for 100 wipes.
To clean the rest of the beast I use a damp (not too damp!) microfiber cloth (the ones that are normally used to clean mirrors etc.) They are washable and you should also be able to get these for about 1 euro at your local supermarket.
I works like a charm - the blackbook looks lean and mean.
**** - I sound as a ****ing cleaning lady