Is there an easy way
 

to find a league to join...and search for criteria?

Well it depends what you are looking for, but at the top of this forum they have a couple stickys with lists of online leagues. You could look through some of them and try to find one that fits what your looking for, or they have a "looking to join a league" sticky you can post in.

or just check out my league ;) Over The Fence Baseball league

You can find easily find the league that's perfect for you by entering your criteria into the search engine of the Interactive Online League Directory.

Filter by specifying your preferences, and the IOLD will give you a list of all the leagues which satisfy your needs. Contact the Commishes of said leagues, and soon you'll be an active owner in a league that's just your style.

Choose the "Advanced search" of the IOLD to narrow down its returns, focusing on your exact desires.