Extraterrestrial liquid water
The Gliese 581 planetary system contains multiple planets that may be candidates for surface water, including Gliese 581c, Gliese 581d, might be warm enough for oceans if a greenhouse effect was operating, and Gliese 581e.
List of extrasolar candidates for liquid water
Further work published in June 2013 suggests that the system has six planets, and that three of them are in the habitable zone.