I've always been a fan of Sourcebans and their open source user-contribution base. Their features like an integrated admin control panel and custom permission groups separate them from any other free or paid ban system today.
One of its only downfalls - besides a lack of seemless integration into a website, creating a need for Sourcebans to be a standalone web application - is that Sourcebans still runs entirely from PHP. Instead of created a redirect to a different web application for bans.foobargaming.com, I decided to make my own ban system from scratch.
FooBar Bans is a Django application that makes use of Django's integrated admin control panel to control permission groups and take the place of Sourcebans' own control panel, while also providing a much lighter, cleaner ban page which is integrated directly into the FooBar Gaming web application.
By creating ban models directly into the FooBar Gaming Django database, we can now check user permissions, donator status, and ban status using only one database connection compared to the previous 3+ connections needed per user.
The source for FooBar Bans can be found with the FooBarGaming.com sourcecode Here on Github.