Dewpoint is a web directory organised by the Dewey Decimal System. It's based on one person's surfing habits but the concept scales extremely well and lends itself to syndicated content directories. All you have to do is define a mapping between your broad customer-orientated categories/channels and the DDC that the directory supplies. See XMLTree for a working example of this. David Mundie, the guy behind Dewpoint, is also experimenting with CyberDewey, a collaborative directory that stores it's categorised entries as XML. Unfortunately, he doesn't have the facilities to run it effectively on his current setup, so if there are any kind people out there who want to lend a hand...