Hi Thom,

xISBN is a great service and all of the others you suggest would be
fantastic. I would put in a plug for a SOAP layer, only because it is
useful for wrapping services like this into non-web applications. Someone
writing an application in VB or wxpython for example, can specify a WSDL
file and get the plumbing put in place to use the service. This can be
done with HTTP tools for the desktop as well, but WSDL support is getting
very strong in this environment. I have also thought about a date
range/sort type of option on xISBN, so if you are matching up something
with a gazillion ISBNs, like "Mark Twain", you could try to slant the
return set to get the most likely ISBN near the top.

art