Valley Games is a relatively new board game company. A few guys run it in their spare time. They take old, out of print board game that are very popular, and they update them and run a printing. So far they've been pretty successful, and they've put out some very good games.
They are currently working on an old title called Titan. Many of you have probably never heard of the game, let alone played it. I've never played it but I grew up on a computer game that was based loosely on the game, Heroes of Might and Magic.
Anyway, one of the owners posted the rules online. He said "because Titan is not yet at print, we can accept any errata changes that you might discover. It always helps having extra sets of eyes looking at our work!" He said these rules were 'near-final', so they'd gone through all the checks at their company, they just wanted the community to double check things.
Can you guess what happened? Titan is a very popular game with some very hard core fans. They are excited about a reprint, but they also don't want to see their beloved game changed in a negative way.
So these fans went through the rules with a vengeance, posting pages and pages of errors they found. I'm sure Valley Games wasn't expecting the level of detail, but they seemed pretty pleased at the response.
Sure, Valley Games could have hired an editor, and maybe they did. But the editor wouldn't have been as invested, nor have the background that the community did. In addition, the community can spread the work. Instead of one person working for days, there are many people working here and there.
Check out the thread where this whole discussion takes place, and scroll down to see the amount of detail and editing that was done 'for free'.
Behold, the power of the community.