Here's a hopeful article from Raw Story about Howard Dean's push back against Breitbart.
Sleeping Giants have been successful at forcing advertisers to blacklist Breitbart by taking screen shots of advertisements that appear next to hate speech on the conservative website. The group then uses the screen shots to shame the advertisers on social media."
Slate has also covered this effort.
This type of push back has been used against Rush Limbaugh. In fact many years ago, I contacted a local credit union whose ad ran in between racist Limbaugh segments (the credit union had simply bought an advertising package that provided for so many ads run so many times per day) and I believe the CU requested to not be on during the Limbaugh air times.
So, if you are interested, put your money where your politics are and make sure businesses know what values you expect of them.