What is a Googol?

Googol =

10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000.

Googolplex = (pages and pages of zeros...)

Named their headquarters Googleplex.

Sources:
Wolfrum Mathworld. Googol. http://mathworld.wolfram.com/Googol.html (accessed March 1, 2007).
Google Corporate Information: Culture. http://www.google.com/corporate/culture.html (accessed March 1, 2007).