Like many of the other posters in this thread, without a doubt, the forum I visit the most (and post in the most) is the Deals & Freebies
section. Deals & Freebies has been the lighthouse guiding me between the Scylla of rampant ebook addiction and the Charybdis of a shoestring budget. I have a soft spot for the entire site, of course, and I always check "New Posts" first, but there's a special flutter I get in my not insubstantial tummy when I see new posts in the Deals & Freebies sections! I love the monthly genre posts, the Kobo coupon posts, the Fictionwise coupon posts, and I miss ATDrake's great KDP posts. Oh sure, there's plenty of chaff that gets in there (heck, I've downloaded a ton of it and posted a little, too), and I'll probably never read a tenth of the acquisitions I've made, but for a few shining moments every day, I am a King, surveying my evergrowing (if wildly uneven) ebook domain!
THANK YOU, DEALS & FREEBIES - I LOVE YOU (and the rest of MobileRead, too - just not as much). There, I've said it, and it feels great (especially if I win). Oh, and how to make it better? More posters, I say, out in the wild internet jungle, scouting for freebies and cheapies that I can add to my ebook kingdom!!!