On Shutterfly, go to your account (or create one), then put the code CARDS4MOM in the promotional codes spot. Then, you can create three 5 x7 photo cards and have them shipped to a single address for just $.99 postage. This offer expires on April 29, 2010. Thanks to The Thrifty Mama for this idea.
Snapfish also has Mother's Day deals. They will will 20% off Mother's Day gifts with the code MOMMY20. Or take 50% off collage posters, T-shirts and flipbooks with the code MOMSAVINGS. These offers expire on April 26, 2010.