iOS: Buycott provides a way for you to keep up with which companies support the causes you support, instead of providing a list of companies to avoid.
The app sorts most companies into “campaigns” that you can join. From there you can see which companies should be supported and which should be avoided. Additionally, you can see a family tree for each company so you know which subsidiaries are part of the parent company. Unfortunately, the amount of information for why each company is categorized in whichever group is somewhat minimal, but if nothing else, it provides a starting off point for your own research.
The iOS version is available now, with an Android app coming soon.