The code below allows only grant access without authentication to a set of IP’s / domains. Any request from a  domain not in this list will be asked to authenticate. Satisfy any allows the .htaccess to grant permission to anyone who meets the two key criteria. In the example you will note that google’s domains have been allowed through so as not to affect SEO too much. Replace 123.123.123.123 with your IP, or that of whoever you wish to access the site. I am yet however to find one that works for dynamic IP’s – wouldn’t that be neat

You will of course need to create a .htpasswd file. a good generator can be found at http://www.htaccesstools.com/htpasswd-generator/ along with a load of other goodies.

#require authentication of requests
AuthName "Restricted Area"
AuthUserFile /var/www/.htpasswd
AuthType basic
Require valid-user
#deny access to all, allow for selected ip's / domains
Order Deny,Allow
Deny from all
Allow from 123.123.123.123 googlebot.com google.com google-analytics.com
#if any of these rules are satisfied they may proceed
Satisfy Any