My company is hiring a software engineer, so we've put together a job description and circulated it through free channels like our friends, local networking groups, Facebook, LinkedIn, Craigslist, etc. We haven't seen as many applicants as we'd like, but we've seen enough to know that some software engineers need a lot of help when it comes to applying for a job with a start-up.
Two suggestions for your consideration:
Don't tell me what you've built - show me.
You're probably working on a product now, right? How about a screenshot? Or a description of how the product solves a business problem? Or at least a link to your company's web site?
Plus - every good engineer I've ever met has some sort of side project or portfolio of prior side projects/products. Seeing your previous work will make me feel a lot better about your future work and make it obvious that software is a passion, not a 9 to 5 thing.
Use the name of my company in your cover letter.
If your cover letter/email doesn't mention Argyle by name in the first paragraph, then I stop reading. Simple as that.