Joey (from our Friends naming batch) is a wonderfully gnarled piece of Olive wood. We didn't try to straighten the board at all - it's crazy and beautiful, as are the standoffs that hold it out from your wall.
We used dark Walnut for the cool tree-of-life pointer. The lettering, we cut from maple, then used black India Ink to get good contrast. And it's raised off the face for a 3-D effect.
Joey is 40" long and 13" high at the ends.