Here's a good general site for Chinese aircraft from 1910's onward
http://www.geocities.com/cwlam2000hk
This one is only in Chinese, but has some very unique photos
http://cwlam2000.netfirms.com/index.htm
Here's one for modern Nationalist airforce
http://www.taiwanairpower.org/
Chinese American organization for perserving WWII air cooperation
http://www.sinoam.com/
The CNAC official site
http://www.cnac.org/
Another Chinese only site - dedicated to the Chinese American Composite Wing
http://www.flyingtiger-cacw.com/
I have some more obscure sites and sources, let me know if there is something specific you are looking for.