Here's a list of plus size maternity online resources:

http://www.jakeandme.com/
http://www.babybecoming.com
http://www.expectingstyle.com
http://www.imaternity.com
http://www.jcpenney.com
http://www.maternalinstinct.com
http://www.momshop.com
http://www.maternitymall.com
http://www.onehotmama.com
http://www.plusmaternity.com
http://www.plussizemommies.com
http://www.maternity-clothing-fashions.com
http://www.motherwear.com

Theres also:
EvaLillian.com
duematernity.com
momsmaternity.com