Have you ever tried to write a simple JavaScript code, like a bookmarklet? Or tried to do something with local files from Firefox?

Normally, the safety policy forbids such behaviors, but if you have a local web server you can get around it. (No! Changing the policy is the most dangerous and stupidest way to get around it, and it is the best way to put yourself in danger.)

So, I remember Python has such module, I was thinking to write a quick one. But you can just do:
cd /path/to/root_files_of_your_web_server/
python -m SimpleHTTPServer

It does the job, you can access via http://localhost:8000/. You can change the port by appending the new port number.

Is this safe? Only if you know your firewall setting. Make sure the port you choose is random enough and/or you do not open that port to public. This quick SimpleHTTPServer listens to all addresses. And create a special directory just for this server, it only contains enough files you need. Do run it at your home directory or root unless you are 100% sure what you are doing.