Searching for an article I read a while ago referencing Ogilvy's "I do not regard advertising as entertainment or an art form, but as a medium of information" quote. It all relates back to conversations and the ideal that can be achieved through online "marketing." Also, now remembering Howard Gossage as I find this ClickZ article by Jeremy Lockhorn, "The First Interactive Ad Man."
Follow-up article here
Another here
Final Here.

Burried in John Battelle's weekly recap is this gem: CraigsList/GoogleMaps mashup.