Extraterrestrial life/Search for life on Mars

There is evidence that liquid water might currently exist on Mars and that liquid water may have been even more common on Mars in the past. Has there ever been life on Mars?

Possible data
Probably the strongest claim that we have data in hand comes from study of Mars meteorite ALH84001. This is the Martian rock first reported in 1996 to possibly contain evidence of fossilized microbial life. It has been estimated that ALH84001 was knocked off of the surface of Mars 20 million years ago during the formation of an impact crater. In 2005 it was reported by Vicky Hamilton of the University of Hawaii that the mineral composition of ALH84001 matches one known location on Mars, Eos Chasma, part of the Valles Marineris canyon system. It has been suggested that this might be a good target for a mission to Mars that would seek signs of past life.

Activities
What other locations on Mars are potential targets for missions that will test for signs of life? Add them to new sections of this page.