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:
This is a trick I’m using at this site that I picked up somewhere on the FeedBurner Forums. I wanted to have my RSS-feed from this site to go via FeedBurner to get stats etc, but I don’t want to communicate the http://feeds.feedburner.com/xxxx URL public since it might change in the future. So instead, in my .htaccess, I have these lines that will redirect all visitors except FeedBurner itself (otherwise it wouldn’t have any chance to read and parse my feed) to my FeedBurner URL.