Do these exist?
If so please name some.
Depends what you mean. If you want long, interesting discussions that take place over years, try some text boards (notably 4-ch) and lurk beyond the first page of each board.
Most image boards are either "the next 4chan" or anime image dumps.
Your best bet is to use something that either is, or is similar to, Overchan.
Unfortunately, Overchan is manually updated, as in, the HTML for the sidebar (frame) is handwritten for updates. This means tediously slow indexing, constantly broken links, and other such similar vexations.
On a tangential note, I wouldn't mind helping with a spider for imageboards. I swear, I hate the entire concept of toplists.
I think toplists are a good idea, they're just abused in stupid ways. I remember when the cool thing to spam was a toplist voting link, or sites would set a cookie to make sure you voted. Second only to those U ARE IN MY VAMPIRE ARMY NOW!!!11 links in terms of annoyance.
yeah, fuck toplists.
what we really need is a webring
This thread is suffocating under the weight of boring people.