Any Fleaflicker user can join a public league. Private leagues are password protected so users must know the password to join. If you create a public league, your league starts out as invisible to other users. After customizing the league rules and settings to your liking, you can make your league visible to the public.
The rules and settings of public leagues must be frozen before other users can join. This is done so that the commissioner doesn't change the rules without notice to gain an unfair advantage. But it also allows you to create custom public leagues with unconventional scoring systems and rules.
It Is Now Preseason '10
Any Fleaflicker user can join a public league. Private leagues are password protected so users must know the password to join. If you create a public league, your league starts out as invisible to other users. After customizing the league rules and settings to your liking, you can make your league visible to the public.