Dan,
As I mentioned somewhere else, patience. I have just finished almost 130 backgrounds for advances, and gave them to Wes to put on his website last night, so maybe they'll be ready today. Included with them are the backgrounds for not just 5 but 9 ages, so anyone can make their own. If you want I can send this stuff to you if you want it in a hurry, but the zip file is over 3 MB.