Just because it's biased towards 0 it doesn't mean there's no entropy in it. Even the raw output of an entropy source based on radioactive decay or thermal noise is biased.

To generate a highly random output that appears independent from the source and uniformly distributed a randomness extractor [1] has to beapplied. The most well know is the Von Neumann extractor.

[1] http://en.wikipedia.org/wiki/Randomness_extractor