Relevancy vs. Intrusiveness
A thought while on the throne: Much of the talk in online advertising has revolved around the Relevancy of ads. This made me think: Profile a customer, know his interests and you can give him/her a relevant ad. Big deal. Throw them an ad that's intrusive it won't work. Contrary to what we've always thought, just because something is relevant doesn't mean it's not intrusive. Combine the two together and something starts working.

Think about internet yellow pages and job sites like Monster.com (shameless plug). The heart of these sites is their advertising, and ironically, that's what makes them so successful (Although Monster has been adding a lot of additional contact to make it less of a commodity). These ads aren't intrusive and are VERY relative.