We found the following links to be most useful:

Twins Help
Dedicated to helping multiple birth families with information, products and services.   http://www.twinshelpstore.com

Kids Love Ohio
A parents guide to exploring fun places in Ohio with children...year round.   http://www.kidslovetravel.com

Twins Magazine
http://www.twinsmagazine.com/

Triplet Connection
http://www.tripletconnection.com