There are actually two threads that bring me back - the "who died" thread; and the "what are you reading" thread. Because people die all the time, and because there are lots of readers on here, there are daily updates. So here I am, pretty much daily.
Oh, and also I subscribe to @Turgenev 's map thread and actually get emails from it; and also somehow get news emails from @Abstruse 's weekly news update posts (not sure how that happens, but am glad of it). So those non-daily notifications also usually bring me to the site.