I use Dropbox but wanted nicer URLs for the links I sometimes send to the files in my Public folder. Each user has a folder on dropbox.com which is publicly shared, like this http://dl.dropbox.com/u/12345/ so I just set up a new sub domain (mine is dropbox.my-domain.se) and let Apache redirect all requests to that domain to my Dropbox folder instead:

<VirtualHost *:80><br />
  ServerName  dropbox.my-domain.se<br />
  RewriteEngine on<br />
  RewriteRule ^(.*)$ http://dl.dropbox.com/u/27215$1 [R,L]<br />
</VirtualHost>