My favorite is the freebies and bargains forum (
https://www.mobileread.com/forums/forumdisplay.php?f=26). I'm afraid to ask for improvements because I spend enough as a result of it.

I used to morer time in the News forum, but too many threads got long with neverending debated on DRM and the like.
One suggestion is that if you post a bargain, and people respond to your thread to talk about the book or author or thank you, it would be nice if you responded. There. I thought of something. I've also seen a post or two where someone asked why a mod removed a post or edited a thread, and there wasn't a post from the mod. I know everyone posts a lot, so you can't always find the time to respond, but sometimes it can keep a forum more lively. Posting bargains is great, but talking about them is even better. I always smile when I see a Robert Walker freebie postef because I want to see what Dr. Drib says.