Sansevieria, more commonly known as Snake Plant. Also know as Mother-in-law's, Devil's, or Djinn's Tongue is so named for the blade-like shape of its leaves.
The erect, up growing leaves make an excellent sharp punctuation or dramatic contrast to billowing mounds of soft grasses, low growing succulents, etc. It also provides shape to pots and planters.
When NASA was looking for plants best suited for purifying the air of long-term manned space missions, Sansevieria proved nearly ideal. Research proved it could absorb 107 different air pollutants including monoxides of carbon and nitrogen.
For those with a predisposition for flora abuse Sansevieria is nearly ideal again: It's drought and low light tolerant, durable, compatible with a variety of soil conditions, and handles neglect like a monk.
Because of the upwards growth of the leaves, it's also an optimal as a feng shui enhancer. This from the Wiki page:
Some believe that having Sansevieria near children (such as in the study room) helps reduce coarseness, while others recommend placing pots near the toilet tank to counter the drain-down vibrations.
Sansevieria comes in a variety of color variations including light and dark greens, with yellow "snaking," and bluish silver. Well suited for an exotic, tropical accent.