We sell to a very narrow segment. I've got Google alerts for loads of phrases and trade show names. We try to attend as many shows as we can. Sometimes with a booth, mostly without...just rocking our own gear and handing out cards. Some have a cheap way to add your logo somewhere to get awareness going.

Once you get a fish on, you'll need a professional sales person to carry the deal forward. Meeting, review, reply, next meeting, follow-up, etc.

Cold prospecting from directories and trade-orgs is another channel. Call,call,call. Then call some more.

And keep pumping the newsletter, opt-in only, keep content fresh.