Re: Coriolis force and the bathtub myth.  Please read:

  * http://www.ems.psu.edu/~fraser/Bad/BadCoriolis.html
for a qualitative argumentation.  This also explains how you could
show the trick to your friends (and then, e.g., claim that the equator
actually goes through your house!).

  + http://www.suite101.com/article.cfm/astronomy/24987
for the approximate size of the force (which, incidentally, is
_still_ wrong, or rather, incomplete: The formula does not take into
consideration the angle of the "horizontal" water surface to the
earth's rotation axis, i.e., a factor of sin(latitude) is missing.

Thus, for all places except the north and south pole, the forces are
even smaller, and they are zero on and somewhere in the vicinity of
the equator.  (Also in the vicinity?  Yes: Remember that the earth
is _not_ a sphere, hence all very small forces tend to be perturbed
"randomly" -- and that means also cancellation -- in quite large areas
near the equator.  Maybe we should try to compute this... when I have
an afternoon of time...!)

Many other links debunking the myth can be found on the internet.

Regards
Harald M. Mueller