First a few necessary recitals: 

1. Dropbox is very useful. 

2. I pay $99 a year for the upgrade. 

3. I use the Public folder to host all kinds of stuff. It neatly solves a problem that's been around forever -- how to quickly and easily put up small files that provide connective glue for the net. I use it for reading lists, my elements of the world outline, default configuration files for software I maintain.  

Now there's a problem with using the public folder this way. Lock-in. Consider that this is the URL of a file in my public folder. 

http://dl.dropbox.com/u/1006496/worldOutline/defaultRootOutline.opml 

What if Dropbox were to go away, or change the terms of use to prevent me from doing this. I'd be S.O.L. because I'd spread these URLs all over the place. I can't redirect them because I don't own dl.dropbox.com. 

I've been worried about this, so yesterday I set up an Amazon S3 bucket to host a mirror of my public dropbox. So I can use this new URL: 

http://dropbox.scripting.com/dave/worldOutline/defaultRootOutline.opml 

Now I can move it anywhere I want, whenever I want, yet still have the convenience of Dropbox.  

Win-win!  

PS: How do I do it? It's a feature of the OPML Editor. Click this link with it running on your machine. Screen shot.