Options +FollowSymLinks 

RewriteEngine On 

RewriteCond %{QUERY_STRING}	!^(.*)key(.*)$ 	    			[NC]
RewriteCond %{HTTP_HOST}	^my\.domain\.se.* 			[NC] 
RewriteRule ^([^\.]+)/?$	/index.php?key=page&username=$1  	[L]

RewriteCond %{QUERY_STRING}	^(.*)key(.*)$ 	    			[NC]
RewriteCond %{HTTP_HOST}	^my\.domain\.se.* 			[NC] 
RewriteRule ^([^\.]+)/?$	/index.php  				[L]

RewriteCond %{HTTP_HOST}	^item\.domain\.se.* 			[NC] 
RewriteRule ^(.*)$		/show_item.php?item=$1  		[L]