Their paper would make a good companion for printing these half-fold greeting cards. These printables come in Word and PDF formats and there are several categories including Get Well, Anniversary, Easter, and Halloween. They have more templates including invitations, thank you cards, and business note cards.
StockLayouts was the 2010 About.com Reader's Choice Awards winner as best source of templates. They offer a few free templates as a way of letting you try out what they have to offer. This is a free greeting card template. You'll need to create an account and log-in to get the free templates.
Use these blank templates in Word or Illustrator. They have several different sizes and folds. Use their templates (paired with holiday papers from The Paper Mill Store) to have your greeting cards commerically printed or print from your home printer. Also see their free templates for greeting cards, invitations, and birth announcements.