new scientist has a nice question and answer section called the last word which seeks to clear up all those little mysteries which i know gnaw at you endlessly, like how long will astronauts’ footprints on the moon’s surface remain there or why do atomic bombs make mushroom-shaped clouds or does getting beheaded hurt as well as other more practical questions. it’s like the straight dope but more scieneriffic. if your particular itch isn’t scratched in the archives ask your own question.