The question I've always had was, "how do you find the early adopters?" for any particular market or product. It's easier to note, when you know where they hang out to talk about the topic (forums, HN, etc). I've also seen the approach of taking out ads, online or offline. Do you guys know of other ways to find early adopters?
I think more work is required for B2B solutions. Linkedin and Facebook probably already have several groups dedicated to the general topic your solution falls under. It's not too difficult to identify people there who are pushing the boundaries of your problem area. These are the low-hanging fruit for finding early adopters. I think networking events, especially if there's a meetup.com group in your area, that are specific to your problem area can be a great place to get some face time with people who might be early adopters. From there, it's a matter of setting up some coffee meetings and talking to those potential early adopters in more depth.
Some people like to throw up a landing page with a form to collect email addresses, then throw money at some ads to drive traffic and see if anyone is willing to send their contact info. I think that strategy has it's merits, but I think you lose something by automating the process at that time. I think there's a lot of benefit from the early face time with potential early adopters. I think you can find out a lot more about who might fit the profile of an early adopter, by actually finding out what an early adopter looks like.