Django is becoming very popular for dynamic websites development (actually it already is) so I decided to start learning it, with the help of a good book. To develop Django web applications you need a good IDE and an environment that support at least Python and a database (SQL Lite, MySQL etc...). If you have multiple machines and you alternate from multiple operating systems, the best thing is using an environment that you can use everywhere, from your favourite browser.
Here comes Cloud9, a very nice service that you could define as the "Google Docs" for developers. C9 offers you a shared, always available on the cloud, environment to write your code. They also offer access to a Linux terminal (so you can install applications, like Django) and your websites are istantly available online for remote testing.
Installing and using Django on C9 is very easy. You just need to open a new terminal tab (ALT+T) in C9 and execute these commands
python ./../bin/django-admin.py startproject myproject
python ./myproject/manage.py runserver $OPENSHIFT_INTERNAL_IP:$PORT
After these commands, your Django website will be live and accessible using http://projectname.username.c9.io (where projectname is the name of the project you just created and username is your C9 user name).