We spend so much time and effort on the front side of our handmade cards. I think it is so important to sign the backs of our works of art. Because that is what they are when we send them out to friends and families. Sometimes other people can't tell that they are handstamped until they see those initials on the back.
Here are just a few of my favorite rubber stamps for the backs of cards:
The Paper Angel has a huge assortment just for crafters that can be easily personalized however you wish.
There are some great etsy shops such as Sweet Paperie.
Another favorite with a totally unique style of their own is Cat's Life Press.
And last but not least, is your own signature or initials in your own handwriting. Just remember to sign the backs and be proud of your efforts!