Try PyChecker, it is a static analysis tool that finds bugs in Python source code and much more.
PyChecker Website: http://pychecker.sf.net
PyLint is another tool that checks if a module satisfies a coding standard, and also makes it possible to write plug-ins to add custom features. In addition to the bug checking that PyChecker performs, PyLint offers some additional features such as checking line length, whether variable names are well-formed according to your coding standard, whether declared interfaces are fully implemented, and more.
PyLint website: http://www.logilab.org/projects/pylint