I worry that the heat from the iron will warp the wood, so I made my own. Here's a link that might help.
Also, if the pad has a lot of "give", it can warp your pressing. A flat board really helps with this.
http://www.daystyledesigns.com/quiltingironingboard.htm
Here's another one that might be a tad easier to make:
http://www.youtube.com/watch?v=2uGVYK-VeNs