INSTAPUNDIT: How Many People Does It Take to Colonize Another Star System? The post provoked a number of responses; my favorite is this one:

The only time I'm tempted to think there's intelligent design to the universe is when I consider how much it looks like it's been designed to prevent cross-contamination of the samples.

And finally, to add to the list of science fiction reference, I'd suggest Robert A. Heinlein's Orphans of the Sky.