Recently dug out and was reading PhilipAndAlexsGuide. Here are PhilipGreenspun's four types of commercial web-sites :
1) *Sites that provide traditional information. * ie content-publishing.
2) Sites that provide collaboratively created information. ie. everything that is currently called SocialSoftware and BroadCatching sites. (NewMediaIsASymmetricalConversation)
3) Sites that provide a service via a server-side program ie. WebServices.
4) *Sites that define a standard enabling a consumer to seamlessly query multiple databases. * ie. information aggregators, search engines.
: Essentially this is the idea which has now become the fashionable pillar of WebTwoPointZero, known as MashUps
See also :