Borrow other people's traffic. Specifically, guest blog everywhere you can, and set up an affiliate program. If you don't want a public affiliate program, that's fine - only open it to certain referrers. For instance, give bloggers with large audiences who you'd like to target a discount code they can share with their readers.
Email/tweet at Smashing Magazine - they're nice folks and I bet they'd mention this, even if just in a tweet.
Edit: I see now that you have been guest blogging. Do it more! It's not just about the traffic you see in the next day - it's also a long term link-building strategy.
Also, don't get down about "only" 5.5k uniques. That means FIVE AND A HALF THOUSAND HUMANS were interested enough to visit your site! Go watch Gary Vaynerchuk's talk at RailsConf 2010: http://www.youtube.com/watch?v=-QWHkcCP3tA
He talks a lot about caring about your customers/audience/whoever (or, as he puts it, "giving a fuck"). Maybe you could put in some sort of "Not totally convinced? Enter your email here to learn more from the founder" mechanism, and then personally email those people, get to know them, and convince them to buy (if it's a good fit). Sure, that's not scaleable, but why not do it right now while your traffic is "low"?