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.
>>7
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.