There's gold in them thar' hills!

Reith, et al, "Biomineralization of Gold: Biofilms on Bacterioform Gold"
Science 313(5784) 233-236 (2006)

Maybe it's because I live in California, and the legend of the Gold Rush of 1849 plays a part in the collective subconsious, but it's always nice to find bacteria, in this case Ralstonia metallidurans that can precipitate gold from aqueous solutions. While this serves as a defense mechanism (the aqueous Au is quite toxic to the little guys), it is suspected that this might be the origin of the small secondary gold grains found around the world. With some good biochemistry, this might be a step towards reducing the environmental impact of gold mining, which has typically relied on mercury, etc (a pollution problem still left over here from more than 150 years ago).