I saw this TED talk a while back and came across it again today. Researcher Kamal Meattle shows how a selection of three common houseplants can result in measurably cleaner indoor air quality.

The three plants he references in the video are:

For a more exhaustive list of air-filtering soil and plants check out this Wikipedia entry. The list was compiled by NASA as part of the NASA Clean Air Study, which researched ways to clean air in space stations.