Firefox Add-on SDK
The Add-on SDK uses python2 and uses 'python' as the executable in all it's scripts - this obviously causes trouble when your /usr/bin/python points to python3.*, and you don't want to change the link to point to python2 as all your other scripts might be using this link.
After searching for a while, I came across this post (where else but on stackoverflow) which explains how to use virtualenv to create a path to python2.7. It doesn't help much because your virtual environment is again overridden by the virtual environment created by the Add-on SDK.
A workaround I used to make it work is to create a virtualenv directory using the command shown in the aforementioned post and copy pip, easy-install and python* binaries from the temp-python/bin directory and put them in the addon-sdk/bin directory.
'source bin/activate' and et voilà!