Sometimes you miss something. This is from 2007 and somehow I missed it.
There's fungus growing in the Chernobyl reactor that's black...and fuels itself off of gamma radiation the way green plants fuel themselves off of sunlight.
It's apparently possible to use melanin to process gamma radiation. If an earth fungus can evolve to do this in a very short period of time (well within a human life time), then what might exotic life forms on other worlds do.
You could even have an entire ecosystem fueled off of radiation rather than light. Where there are plants there can be animals, after all. Such an ecosystem could exist deep underground in a "hollow earth" type scenario or in radiation-heavy parts of deep space. This kind of life form might grow on comets - most comets have plenty of water, which would still be necessary.
With proper genetic engineering, this fungus also has other possibilities. Could a variant be bred that will actually eat nuclear waste? Another suggestion would be to breed an edible form - which might be handy as a food source on deep space missions or in the initial stages of colonization.
And if one wanted to go really out there, could it be possible to engineer animals to pull the same trick? Maybe even...people?