Here's a couple of links with league listings. The best thing to do is surf around looking for leagues that look solid and leagues that need owners. I'd check the forums of each league for activity and the rules to see how well thought out the league is. If the guy put alot of time into the rules, he most likely will be dedicated to the league.
<a href="http://www.ootp-leagues.com" target="_blank">www.ootp-leagues.com</a>
<a href="http://www.ootplinks.com" target="_blank">www.ootplinks.com</a>
Hope this helps.