Danger signs ? What danger signs ?
FIXME: I want some nice public-domain images of
More subtle danger signs:
http://www.elvis.ac.nz/brain?DangerCompSciGraphicCompetition
Pretty waves reflecting the sun … hello, what’s this ? It’s not my fault! 

“anything radioactive: Exploring the fun side of nuclear radiation” http://anythingradioactive.com/