Using MyLeague.com's browsing tool I have compiled a list of all the leagues with 100+ players. (as of April 1st)

-------8 BALL-------

Elite Pool League

 - 

http://www.myleague.com/epl

Admin - Boomer

League Room 1

-------9 BALL-------

Vampire League

 - 

http://www.myleague.com/vampire

Admin - The Vampire

Room 2

9 Ball Crew

 - 

http://www.myleague.com/9ballcrew/

Admin - Supa_Playa

Italian Room

AVENGERS

 - 

http://www.myleague.com/avengers/

Admin - Hawkeye05

Room 3

-------Snooker-------

FOD Snooker Association

 - 

http://www.myleague.com/fsa

Admin - SnookerMan

Snooker Pro League Room 3

Leagues are great and don't be afraid to join

Snipe

 

PS. This is not a joke :p