Once when I was job hunting, I sent a resume to a company that I felt would be a good match. No response. Then about a month later, this company runs an ad for an engineer. So I send my resume again. No response. Finally, I accept a job that requires me to move out of the area, and after doing so, get a phone call from the other company asking me if I can come in for an interview. So that's how it works.
Another company looked to be one of the few in my area that did anything like what I was doing, so I sent them a resume. No response. A month or so later, I saw an ad that looked like it fit me to a tee, but didn't include a company name, so I faxed a resume to the listed fax number. No response. Upon using reverse lookup, I discovered it was the same company I'd already contacted. As best I could figure, I was the best qualified person in the whole state for that job, and couldn't even get an interview with them. So it goes. Don't give up, keep sending stuff out and be patient. There's probably not a lot you can do to spur along the ones you've already contacted.