My first contribution is by Piet Hein
http://www.leptonica.com/cachedpages/grooks/grooks.htmlASTRO-GYMNASTICS
Do-it-yourself grook
Go on a starlit night,
stand on your head,
leave your feet dangling
outwards into space,
and let the starry
firmament you tread
be, for the moment,
your elected base.
Feel Earth's colossal weight
of ice and granite,
of molten magma,
water, iron, and lead;
and briefly hold
this strangely solid planet
balanced upon
your strangely solid head.