http://tinyurl.com/9e6j6 This is a picture of a woman on a fitting bike in aggressive and relaxed aero (aerodynamic) position. What she's holding on to are aero bars.

I think they are frowned upon in pace lines because you can't react as quickly. But my hands fit right under them, so I can still hold on on the regular bar, or on the hoods, or on the drops. Gives me lots of different hand/wrist/back positions so I don't get as tired.

Nanci