Kudos, file sharing, and a customer profile
I'm not a PDF publisher but I'm definitely a major PDF consumer having purchased at least 30 or more PDF's and to be honest, many if not most of the PDF's from the publishers who've chimed in so far:
Libram Equitus I & II, all 3 of the 101 books from PJR, all but two of the Natural 20 Press releases, most of Monte's releases, Book of Broken Dreams, Requiem for a God, Bob's Book of Enchantment (looking forward to the next book from you), Enchiridion of Mystic Music (still waiting for the next Enchiridion book), Forgotten Heroes - Paladin (this one is excellent), Thee Compleat Librum ov Garudok's Necromantic Artes (please make the next one have an easier title

, both Dollar Dungeons, Everyone Else, Book of Curses, Swords Into Plowshares, NPC Essentials, Portable Hole Full of Beer... ok that last one was free but you get the idea. And as is, I think I've still left quite a few of the ones I've bought off this list.
So first, kudos to you guys who write and publish this stuff because I've been loving the PDF's I buy and as DM for our group I can tell you that the players have been loving the material as well (in fact they're getting a few of the books from 101 Spellbooks and a couple items from 101 Mundane Treasures in this weekend's game). Last session was my first as GM and the one new thing I brought as DM that they enjoyed most was the maps made with Dollar Dungeons. The party paladin has dang near been living with Forgotten Heroes - Paladin and the bard is absorbed by the Enchiridion of Mystic Music. And in case I haven't listed one of your products in this paragraph, don't feel bad... I've only had one session so far with the next being this weekend but I know we'll be heading to town shortly and there's a necromancer waiting for them so I'll be pulling from quite a few other products soon.
And finally for file sharing... Having said all I have above and listed just some of the PDF's I've purchased, I'll also tell you that I download PDF's via Kazaa. Obviously it's not PDF's for sale at RPGNow because I've purchased about half the D20 PDF's they sell.

No... what I download from Kazaa are PDF versions of hardcopy books I already own. Very handy being able to print off a couple pages from one of the books for reference during the game rather than having to go rifling through half a dozen books to find the rule/magic item/spell/critter I'm looking for. I'd make the PDF's myself but don't have a scanner and don't want to pirate a copy of Adobe Acrobat to make the PDF's even if I had a scanner.
Now, I'm not so foolish as to think that most of the folks who download D20 PDF's use them the way I do but when you see them up there (and no, I don't make them available for download from me once I've downloaded them), remember that there are folks like me who only download the PDF's of hardcopies they already own.
One last note... yeah, I buy the hardcopy books like I buy PDF's... I think my bookshelves are wishing death upon me the way they've been groaning from the weight of books on 'em.