I'm always watching ad agencies and social marketing firms to see how they're adapting the latest web tools. Why? They're in the business of selling things: products, ideas, even sentiment. It's one of the reasons I haven't missed a single episode of Mad Men. I'm endlessly fascinated with what drives trends, and more importantly, our inevitable acquiescence to many of them.

Content is content, whether it's straight advertising or strictly editorial, or something in-between. The challenge, as it always has been, is to get yourself noticed. To engage an audience, convert them, and ultimately cause them to evangelize on your behalf.

One of the more clever campaigns I've seen recently is Old Spice. Now here's a product that's been around since forever, that has always evoked an image (at least for me) of a stogy "salary man" type with pomade in his hair and stale cigarettes on his breath. Need a reminder? Take a look at this vintage commercial from the '50s.

On top of a legacy brand image, Old Spice has plenty of more youthful contenders to deal with now. Axe has spent millions of creative dollars to build a very loyal, sticky audience of tweens, teens early 20-somethings. Dove has entered the market with a slew of mens products, signing MLB star Andy Pettitte as a pitchman.

And yet Old Spice is succeeding. In the past 18 months, Old Spice has become the top-selling deodorant and antiperspirant for men, according to ACNielsen. This is in no small part due to a hilarious series of web videos that integrate social media. The latest: send Old Spice questions via Twitter and get video answers. (See more below.) Its Facebook page has more than 500k members, where thousands of people have shared content and participated in discussions. (Axe only has 270k members.) Not bad for a 71-year-old company.

What does this mean for those in the content biz?  Whatever you're selling -- whether it's breaking news or consulting services or bedazzled headbands -- come up with an irresistible way of letting people know.  Invite them to participate, and then act on that engagement. Be original, be smart, be funny and be current.  If Old Spice can reinvent itself in a recession and with so much competition........why can't you?

Wieden+Kennedy, the Portland, Oregon-based ad agency, created the campaign.

UPDATE: Just after I posted this, Mashable and Kevin Rose (Digg) published stories about how the Old Spice guy is making custom social videos. Mashable story here. Digg here.