Surprisingly, “Hillary Clinton dropped her Web display advertising efforts completely,” according to ClickZ’s Kate Kaye.  This doesn’t mean she’s broke – reports indicate that Clinton has raised more money than everyone other than Barack Obama – but the move still left just two other candidates to be tracked by Nielsen//NetRatings (which supplied the original data).

Those candidates are John McCain and Mitt Romney.  Kaye reports that “Romney ran about 3.4 million impressions of four ad creatives.”  In contrast, “McCain’s campaign, which ran about 8.7 million impressions in May, still appears to be testing a variety of ad creatives and sizes, placing ads on the same sites and networks as in April.”

Kayte goes on to give extensive information about (and samples of) McCain’s ads, and it really is an impressive effort on the candidate’s part.  Yet I usually don’t even look at ads, never mind click on them or let them influence a decision; for reasons like this, I should point out that the Nielsen//NetRatings data is open to interpretation, and that Web ad buying alone isn’t likely to carry the election, anyway.

Still, it’s interesting (and somewhat encouraging) to see a candidate embrace the Internet as an advertising medium.