I came into a recent issue where I wanted to hide ?id=xx from the query string of a URL so I could use a single Facebook Comment Plugin with different data. I fixed the issue by using a few lines of code in a .htaccess file.
If you have various password protected pages on your website, but want people to Like your pages (via Facebook), there is a simple trick you can use to allow this.
A while ago I had to sync files from one server to another. The reason? I was responsible for moving all the application and websites hosted on a old server to a new, faster server with better security and a updated operating system.