USED BILLBOARDS LATELY?
Google doesn't advertise much. (Doesn't need to: talk about viral marketing gone wild.) But when it does, it does it in typically unconventional ways.
Take recruitment advertising, for instance. When Google went looking for software engineers they didn't just rely on a recruitment consultant, or an ad in an industry mag. Instead, out of the blue, billboards and posters appeared at strategic positions near the major technology centres in the US (on highway 101, in California, and a subway stop in Boston, Massachusetts, for example) carrying the cryptic message:
{first 10-digit prime found in consecutive digits of e}.com

Most normal people simply shrugged their shoulders and moved on. Those who nutted out the answer (7427466391, if you must know) were confronted with yet another mind-straining puzzle.
The reward, for those who cracked it? An invitation to apply for a job with Google: "One thing we learned while building Google is that it's easier to find what you're looking for if it comes looking for you. What we're looking for are the best engineers in the world. And here you are."

What I'm getting at is, you can look at your promotional choices as a series of filters by which you pare down the audience to just those people you most want to talk to - that is, those people who are most likely to buy from you.
In this instance Google used its message to do the filtering, with the geographic positioning of the outdoor advertising being another filter.
Now, I wouldn't presume to suggest that outdoor could work better for your promotions than the likes of Reseller News or its stablemates. In fact, PC World once upon a time resorted to using billboards to get its message across. In that instance, it was to reach potential readers amongst the general population. That promotion, in conjunction with a range of other activities, was very successful.
In fact, for most of you reading this, the advertising medium you choose is, by default, the primary audience filter, right? (OK, we've all seen ads where we go: "why did they put that there?" Amongst geologists, a rock that appears completely out of place is called an 'erratic' - a term which seems to apply equally well to highly technical ads in broad consumer media.)
By choosing the medium to pre-filter your audience, you can invest your precious content in getting your message across, rather than simply filtering, as Google did. Of course Google well-served its brand by way of the brain-teaser, but that's another story.
First published in Reseller News.