The tags are super simple to make, I just created a PDF on InDesign, with spaces to fill in each child's name, age and height for the year. (I'm sure you could easily do this in Word as well - or let me know if you'd like the file and I'd be happy to share it!)
Once the file was created, I printed them on my home computer on colored card stock, cut each tag out with a paper cutter, rounded the corners and added a hole punch for the tags to hang by.
When we gave them to my family, we gave them 20 tags per child, each with their own designated color. I figured they'd probably use the growth chart until their children were about 15 or 16 years old (give or take), and there might be a mistake or two marking the tags, so I wanted to give them a few extra. I also sent them the PDF file after the fact, so as they have more children, they can easily make more tags.
Mike and I also included a package of small gold nails for each child, to hammer into the growth chart and hang the tags on. (We purchased them from Home Depot.) I've seen people use hooks as well, but I couldn't find any that were "dainty" enough to match the tags. I store mine in a small striped pouch I received from a friend a while back.
P.S. Wanna see how long I sat on these pictures? I accidentally took the below pic while I was trying to photograph the tags and it actually turned out kinda cool ... I was 38 weeks pregnant.
Whoa. Hard to believe I had that belly.