I don't know about you, but I like the 'extended' search results I sometimes see on Google. I mean the ones where Google, instead of just offering a single link for the top search result, provides you with several deep links into a site. It makes navigation faster, and that's a good thing.
Those extra links almost always show up in organic results, so you may not have known that marketers can actually buy this feature in their paid listings as well. Google calls them 'AdWords Ad Sitelinks.' But — I'm starting to wonder how well these actually work for marketers. I noticed today that in Google's case study about how Nationwide Insurance used Sitelinks [pdf], Google says the clickthrough rate went up 73% but conversions only rose 60%. The case study isn't clear on whether that's conversions per click or overall conversions — but it certainly sounds like overall conversions. In which case, the clicks Nationwide got from Sitelinks actually converted at a lower rate than the clicks they got from traditional paid listings.
Now, this is just one example — and as I said, it's based on my reading of the case study. But if Sitelinks really did drive conversion rates down rather than up, surely that'd be a concern.
I'm curious — have you used Sitelinks? If so, what did you think of the program's performance — especially the conversion rates? Let us know in the comments below.