Four Day Planet on LibriVox. I'd never heard of Piper before, and really just picked the book at random from a list of sci-fi titles that had recently showed up on the site. Of course, that's the wonderful thing about the internet - churning up all sorts of wonderful (or even mediocre) stuff that you've never heard of and serving it up free of charge. Between LibriVox, the Internet Archive and GoogleBooks, I defy you not to stay entertained with a computer and hi speed connection. Anyhow ...
Four Day Planet is not fine literature - it's not even among the better scientifiction that I've read (or listened to, in this case). The dialogue is stilted, the plot is okay as it goes - nothing ground breaking, but told competently - and the characters are pretty wooden. So why would I recommend it? Because it strikes me as a wonderful "gazetteer" for games like Traveler - a really well realized and interesting setting for science fiction games.
The "four day planet" of the title is Fenris - inhabitable by humans, but only just. It has a four day year, spending half of it as a boiling hell hole and the other half as a frozen iceball. There is native life, mostly in the oceans, and humanity living in a large bunker-city. The main industry of the planet is the collection and sale of "tallow" - a waxy substance taken from massive sea creatures called "sea monsters". The tallow is collected by monster hunters, guys who work on "boats" that act as both submarine and aircraft - in essence, futuristic whalers. What Piper lacks in storytelling or characterization, he makes up for in a fantastical-but-believable science fiction world and universe.
If you're a Traveler player or enjoy semi-realistic sci-fi, I suggest giving this one a listen or read. You can also find it on Project Gutenberg or buy a copy at Amazon.