And that's really all you need for the basic New Year's Jar. You can make a tag with the current year on it, and attach that to the jar somehow. But you don't really even have to do that.
We write on the cards all throughout the year. You can write about anything... memorable moments, blessings, achievements, funny things, etc. We like to keep it positive around here. And then, on New Year's Eve (or New Year's Day, around the table, etc), we open the jar and take turns reading the cards in it. It's fun to look back and remember some of the moments -- big and small -- that have happened to our family.
If I get really ambitious, I can make fancier year tags, but if not, these will do. I can't wait til New Year's day to see what has been written down throughout the year!