RewriteEngine on

RewriteRule .*index.php.* - [L]

RewriteRule ^(.*)/tag/?([^/]+) index.php?blog=$1&action=tag&value=$2 [L]
RewriteRule ^(.*)/about/? index.php?blog=$1&action=about [L]
RewriteRule ^(.*)/entry/?([^/]+) index.php?blog=$1&action=entry&value=$2 [L]
RewriteRule ^([^/]+) index.php?blog=$1 [L]

RewriteRule .*admin.* admin.php [L]
RewriteRule ^(.*) index.php [L]