I recently needed to find a quick, simple way to download some files from my seedbox - a server that simply downloads torrents and then I can either watch them in Plex (for example new episodes of an Open Source TV show) or download them to my computer over HTTP.
The simplest way I could find is by using Python! Let's say we want to open up port 12345 for this purpose, what we would do then is open a terminal in the directory where the files live (let's say it's /var/media) and run the command to start a HTTP server on port 12345 listing the files in /var/media:
cd /var/media python -m SimpleHTTPServer 12345
You'll now see something like this:
Serving HTTP on 0.0.0.0 port 12345 ...
All you need to do then is go to your server, for example http://yourserver.com:12345/ and you can easily download your files from there.