Panspermia isn't a crazy idea, especially when we seem to keep finding extremophiles that can survive in very harsh environments. The components of life may be traveling between planets or solar systems at a non-zero rate, seeding the universe with living materials. That said, life is still relatively fragile, but there may be some optimism in finding living specimens elsewhere than Earth. (First, though, we have to make sure we're not the ones contaminating our own solar system.) Here are just a few links on various organisms that might survive a trip in space -- without a space ship.
If you'd like to read more awesome and interesting stuff, check out this unrelated (but not entirely random!) Techdirt post