Mod rewrite tips for SEO

One of the bonuses of attending the WMW Pubcon is that they mail attendees a cd of all of the PowerPoint presentations that were used in the sessions. One of the presentations was by a company called TrueLocal, where they discussed using mod rewrite for various things. Now, I do not claim to have much knowledge about mod rewrite, so I cannot explain any of the code they showed us. But, I thought you might like to have the code in case you need it. So, without further explanation, here it is.

Folder move (redirect) - moving a folder from an old location to a new one:
RewriteRule ^olddir/(.*)$ /newdir/$1 [R=301,L]

Serving content transparently - shortening urls for search engines
RewriteRule ^([^/]+)/(.+)$ /file.php?Dir=$1&file=$2 [L]

Deny access to an IP:
RewriteCond %{REMOTE_ADDR} ^123.45.67.[9]$
RewriteRule ^/.* - [F]

Serve Different Content to a UA/IP:
RewriteCond %{HTTP_USER_AGENT} ^Jakebot
RewriteRule ^page1.html$ /special-page.html [F]

Serve Image Based Upon Referrer - Prevent image theft:
RewriteEngine on
RewriteCond %{HTTP_REFERER} !.*/valid-page.htm
RewriteCond %{REQUESTED_FILENAME} ^specific-image-name.jpg$
RewriteRule .*.(gif|png|jpe?g) http://www.example.org/funnypic.jpg

Please make sure you backup your .htaccess file before adding this code to it, in case you need to revert back.