MarketingSherpa is out with a special report on subscription-based B2B sites.
Subscription sites are in vogue these days, especially for B2B. I know of at least a dozen subscription-sites that cater primarily to small businesses, and I belong to a few myself.
The MarketingSherpa report covers a wide variety of issues relating to marketing B2B subscription sites. Today I’d like to focus on just one of the charts.
The following chart outlines the best sources of traffic to B2B subscription sites:

The way this chart is organized, the best sources of traffic appear in the top right quadrant. The farther to the top and right a particular traffic tactic appears, the higher the quantity and quality of traffic from it.
As you can see, the best return comes from search engine optimization (SEO). Next is paid search marketing (pay-per-click ads). After that is online banner advertising and sponsorships.
The surprise to me is that viral marketing is almost neck and neck with online advertising, and appears among the top four tactics to grow traffic. I would not have expected viral marketing to play such an important role for B2B sites (B2C yes, but not B2B).
Public relations was kind of middle of the road. The sources of traffic that were lower quality and quantity included affiliate marketing, offline advertising, co-registration, and rented email lists.
While this data relates to subscription websites, I suspect you could draw some correlations for any kind of B2B site.
The report is open access until June 5, 2008. See also the accompanying charts including a larger version of the above chart.