This is from where I moved from /post/post-name/ to /posts/post-name.html. And the same for /projects/ to /projects.html and so on.

gistfile1.apacheconf

<Directory "/var/www/site">
    Options +FollowSymlinks
    RewriteEngine on
    RewriteRule ^post/(.*) http://nickcharlton.net/posts/$1.html [NC]
    RewriteRule ^projects$ http://nickcharlton.net/projects.html [NC]
    RewriteRule ^about$ http://nickcharlton.net/about.html [NC]
    RewriteRule ^archives$ http://nickcharlton.net/archives.html [NC]
</Directory>