One of the things that is recommended when I attend church, is to write a letter to yourself after your baptism, stating the reasons that you were baptized. Years later, this may be an important letter to you. Perhaps, you could print the certificate on one side of a sheet of paper, and leave the other side for writing the letter, and fold it in half so that behind your certificate in your Bible, is the letter your wrote to yourself about your baptism.
Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: teaching them to observe all things whatsoever I have commanded you: and lo, I am with you always, even unto the end of the world. Amen. -Matthew 28:19-20
Here is an example of one that is filled out:
(The example "Main Street Church of Christ" could of course be a river or lake, "Missouri River" or "Lake Tahoe" or wherever)
As usual, the wonderful frames come from thegraphicsfairy.com-- there are so many pretty borders and frames to choose from over there so be sure to visit!