I think outbound marketing techniques are getting less and less effective over time for two reasons. First, your average human today is inundated with over 2000 outbound marketing interruptions per day and is figuring out more and more creative ways to block them out, including caller id, spam filtering, Tivo, and Sirius satellite radio. Second, the cost of coordination around learning about something new or shopping for something new using the internet (search engines, blogs, and social media sites) is now much lower than going to a seminar at the Marriott or flying to a trade show in Las Vegas.
Rather than do outbound marketing to the masses of people who are trying to block you out, I advocate doing "inbound marketing" where you help yourself "get found" by people already learning about and shopping in your industry. In order to do this, you need to set your website up like a "hub" for your industry that attracts visitors naturally through the search engines, through the blogosphere, and through the social media sites. I believe most marketers today spend 90% of their efforts on outbound marketing and 10% on inbound marketing and I advocate that those ratios flip.
The best analogy I can come up with is that traditional marketers looking to garner interest from new potential customers are like lions hunting in the jungle for elephants. The elephants used to be in the jungle in the '80s and '90s when they learned their trade, but they don't seem to be there anymore. They have all migrated to the watering holes on the savannah (the internet). So, rather than continuing to hunt in the jungle, I recommend setting up shop at the watering hole or turning your website into its own watering hole.