At 11:27 AM 8/29/02 -0700, you wrote:
I'd like to give readers the choice of where the ISBN links go to. ...
It's actually easier to implement as a special page as Brion points out: ISBNs will generate a link to "/wiki/Special:Booksources?isbn=XXXXX", and that special page will have links to Pricescan, AddAll, Amazon, or whatever else we feel like adding, and even text explaining the different benefits of each site.
Perhaps a link [Find the book] with links to Library of congress, CARL, AddAll, Addall Used, Pricescan, ABEbooks, etc. Some of these will find used books, some will find copies of books without ISBNs.
Fred Bauder