I finally got a Pinterest idea off my board and into real life a few weeks ago!
Unfortunately, this was the best picture....
We stained a 1x6 6 foot length of Poplar and then I marked off the lines with black Sharpie. The numbers I did by printing off the size and font I wanted and then tracing them with a pencil overtop the wood so that it left an indent in the wood. I then filled it in with the Sharpie and finished it with some poly clear coat. We marked it with the sharpie and let my daughter write her own name.
This was so simple and so much prettier and more durable than a paper growth chart (and more portable than marks on the door casing!).
The original site I pinned from is here. I also had pinned from here, but apparently its not a tutorial; if you don't want to make your own, they sell them though I believe.