RewriteEngine on
RewriteCond %{HTTP_REFERER} ^
http://(www|directory)?\.google\.com
RewriteRule .*
http://www.whereyouwantit.com [R,L]
redirect from google search and google directory
Edit:
you can tweak it a little for country specific google domains like google.ca google.de etc. etc.
RewriteEngine on
RewriteCond %{HTTP_REFERER} ^
http://(www|directory)?\.google\.[a-z]{2,3}/
RewriteRule .*
http://www.whereyouwantit.com [R,L]
this one should be OK