Mother-In-Law's Tongue, Areca Palm, Money Plant
These are the three plants I have out of my 99 things. I went to a plant nursery and bought them after my friend David pointed me to this TED talk: How to Grow Fresh Air in which three plants are recommended for not only producing all the fresh air you need, but also filtering out almost all air pollutants.
They didn't have a money plant, so I bought a rubber plant instead. Technically you're supposed to have a bunch of each of these plants per person. Well, whatever. They have funny names, live indoors with no maintenance and no direct sunlight, are difficult to kill, and might be making the air a little cleaner.