You can read more about the Google SOAP API key
here. You can check a web page's Google ranking without a SOAP API key at this
new Google page rank page.
If you're so inclined, you can read about APIs on
this Wikipedia page, and about SOAP on
this page.
EDIT: I highly recommend if you want to track your web site's stats getting a Google account and signing up for
Google Analytics. They'll give you code to insert into the pages you want to track. Probably the best stats package out there, particularly if you're using adwords.
Vasily