Stampin' Up!'s Envelope Punch Board makes a fabulous gift card holder!! So easy.
DIY gift card holder tutorials - AndreasNotebook.com
Origami envelope or gift card holder: More
MINI Envelope Gift Card Tags ... use Envelope Punch Board to create the envelope
2 Easy DIY Gift Card Holders for Christmas or Birthday Gifts! | @karenkavett
Gift card holder, photo tutorial available on the blog: http://www.kristycoromandel.com/pop-up-gift-card-holder/
Make your own envelopes. I have some awesome paper scraps lying around just for this.
Template for Laminate and Sew Gift Card Envelopes from Cathe Holden on SC Johnson's Family Economics blog. Photo courtesy of Cathe Holden.
Easy folded gift-card tags, by Amber at Damask Love: http://www.damasklove.com/modern-bright-easy-gift-card-tags/
Free printable mini envelope template - making my own money bags for Tet