Kamal Meattle used three just three indoor plant species to increase oxygen, filter air, and boost general health at a a New Delhi business park. You can use them, too, in any indoor environment.
Meattle's presentation at the TED 2009 conference details a large-scale success, using thousands of plants for hundreds of workers. In any living or working space, though, the three plants—Areca palm, Mother-in-law's Tongue, and a "Money Plant"—can be used to convert carbon dioxide into oxygen, remove organic compounds, and generally filter and freshen the ambient air. A single person looks to need a minimum of 11 total plants, and certain climates with less sunlight could require a bit of hydroponic growing, but Meattle swears by the health, productivity, and atmosphere benefits. Check out the detailed slides from his TED talk: