As a Dropbox user, I often need to start a web server from a non-standard root folder location. Under Windows, I have been using Mongoose and loves it. Mongoose is a single .exe file that can be put into the root folder of a web project.
For Mac and Linux with Python, life is even better. A light weight server is already installed. I just need to run the command
sudo python -mSimpleHTTPServer 80
and the web contents can be accessed through the URL