When I ramped up my airline software company in the late 1980s, I discovered a most powerul sales tool, the sales letter. I sent them together with a newsletter to the MIS managers at airlines, and followed them up with phone calls asking for an appointment during my next trip. Despite many mistakes - like making them too general - I got awesome results.
Do sales letters work in staffing? I'll bet they do, and I welcome comments on this from anyone actively selling in the market today. Bob Bly, a professional copywriter, makes a compelling case for sales letters, and in this blog post he makes the case for longer letters.