Flake8Lint (available for Vim and Sublime Text 2) works really well for me, and my co-workers. The optional complexity checking is a nice bonus. You also get the PEP 8 linting and some logic checks. It hurts at first, to see all the errors pop up, but once you tweak the settings (maybe you don't care so much about PEP 8 spacing and you'd like your equals signs to all match up, in which case it's simple to ignore those issues), it can help keep code consistent. I think the big win is on large projects with a number of people writing code. Having an enforceable "style" really helps cut down on bugs and makes everything more readable.