In the dog-eat-dog world of alcohol, it would make sense that companies would try to keep out the competition. Yet America's craft brewers are routinely turning toward rivals to collaborate and create limited-run brews that highlight each brewer's strengths.

Collaborations invite camaraderie and companionship to smaller breweries, where the work can be a solitary experience, or in the case of a larger brewery, the opportunity to break free of the corporate routine and just...