Here is a way to Block/Ban any visitor to view your website using .htaccess  file.You can block a singal ip or complete rang of ips of any host to view your website.Now you can easily Block a person who clicks invalid on yours adsense ads for blocking pursose.Just put hi ip or ip range   in .htaccess file and that person never access your website.

Here is a simple .htaccess file for blocking a single ip

Block a Singal IP Address.

This will block get or post access of a singal ip adress

order allow,deny
deny from 127.0.0.1
allow from all

Block Multiple IP Addresses

To block multiple IP addresses, list them one per line.

order allow,deny
deny from 127.0.0.1
deny from 127.0.0.2
deny from 127.0.0.3
allow from all

Block a Compleate Range of IP Addresses of any Host.

This will block a Range of IPS From 127.0

deny from 127.0

this will block complete range of IP From  127.0

Block Visitors From Spacific ISP by ISP name

deny from isp_name.com