Mindfulness for your work: http://focusr.co/ (i.e., instead of being mindful to your breath or some aspect of your environment, you can practice mindfulness by bringing your attention back to your current task).
This is especially useful because it prevents downward spirals from happening before they begin. For example, if you want to work on X, you can write "Do X" in this extension. Then, when you open a new tab to do something non-productive (like browsing reddit, etc), you'll see a huge reminder of "Do X" to prevent goofing off before it even happens.
I think flow is the more the state achieved, whereas mindfulness is learning to notice when flow is not achieved, or is achieved for the wrong thing.
For example, I can be in flow while coding, but if things get too frustrating I may drop out of flow. Mindfulness for me is noticing quickly that I am frustrated. If I don't, I may end up in flow while reading Hacker News; being mindful helps me recognize that state rather than getting caught in it until noprocrast boots me.