The only thing I can get python omnicomplete to work with are system modules. I get nothing for help with modules in my site-packages or modules that I\'m currently working
While it's important to note that you must properly set your PYTHONPATH environmental variable, per the the previous answer, there is a notable bug in Vim which prevents omnicompletion from working when an import fails. As of Vim 7.2.79, this bug hasn't been fixed.