If people really want to grow PDF awareness, there is one surefire way to get it noticed. Take a page from Gold Rush Games and take it a step further.
As an Action! System and D20 licensee, I've had to pick up a few dual system products to take a good look at how it has been done in the past. One of the products I picked up was Thing at Ridley Manor in PDF format. As I went through it, one thing I noticed was the plethora of small ads embedded throughout the product, in sidebars, at the bottoms of pages, etc. 8 such ads in 18 pages, plus a full page ad on the last page.
Seems like a questionable advertising tactic for a product people are paying for, but it occurs to me that this tactic may actually be a good thing under the right circumstances. Those circumstances are print publications. Whether using traditional or POD printing, it is expensive to add an extra page of advertising or catalogs to the back of a book. However, there always seems to be a bit of dead white space floating around on many pages of a book, and these spaces are big enough to drop in some sort of advertising.
So that's the idea. when PDF publishers go to print with one of their products, drop some of this sort of advertising into the book. Not a lot, just a little, as I think now thatGRG's usage is rather close to overkill, with almost an ad every other page. If enough of us stick to this concept for a sufficient length of time (I'm talking years, not weeks or months), I think the PDF market will eventually see some noticeable improvement. Don't have enough product to fill more than 1 or 2 of those spaces? Drop an add in for RPGnow, pointing to your manufacturer page. Or swap space with another publisher.
Another thing I want to point out is that this and several similar threads in the last 6 months have all been discussed revolving around a single improper expectation. A lot of people seem to be under the impression that doing something to improve the industry should produce instant results. That isn't the case, folks. Even the publisher pack being advertised in Polyhedron is a short-term project that isn't likely to produce significant results within its given timeframe. If you want to see the PDF industry improve, you need to stick to your guns for a few years, not a few weeks or months.
Going back to the publisher pack, while running it for a short duration in Polyhedron is the right way to handle it, that shouldn't be the end of handling it. After the 12/1 deadline passes, there should be advertising in another magazine, same package, different coupon code and duration. When that deadline passes, do the same thing again, etc. Expecting it to accomplish what you want in just two short months, well, you may as well wander over to the local church and threaten the priest into performing miracles, since that will be about as effective.
Since this soap box is starting to creak and teeter, I think I'll get off it now.