Umm, for those who havent read it:

A disturbing manga inspired by an even more disturbing movie of the same name (aka Suicide Club). As you might expect, they both deal with the theme of suicide. However, the plots of the manga and movie are significantly different, so don't wory about spoilers and such. Finally, I'd just like to point out that the manga isn't for the faint of heart, and the movie even more so.

Haven't read the Jisatsu Circle yet (stupid torrent has no seeds) but I think that Kamakiri may be a bit of what you're looking for.

Current avatar features Badou from Dogs.