Here is a simple project that I am using for my own wedding with the favor boxes. If you have tons of labels lying around, this is a nice way to incorporate them at no expense to you!
You will need:
computer and printer
decorative hole punch
Go into your word processing program. I use Microsoft Word. Under Tools, click on Labels and be sure that you select the correct code for the labels that you have. Decide on what font you want to use. If you want more variation than the fonts you already have, go to a site that lets you download fonts for free. I like Dafont.com. You can also download cool symbols as well that you can use like butterflies and beach themed shapes for whatever your celebration might be.
I have chosen to just use the "C" in the wedding colors of red and teal.
Once you have selected your font and made your labels, print them out.
Here, to punch out the monogram, I am using a circle punch with a diameter of 1 inch.
Once, you are done, affix to the box and you are done!
Now, you can get even more complicated with this by adding other embellishments. For me, I wanted to keep it clean and simple. ( I have a lot of these little buggers to do!)