I just realized the latest chapter I posted for "High School Massacre" on SOL ends with a cliffhanger.
Cliffhangers are discussed sometimes in the SOL Forum. Some people like them, others hate them. One author on the forum (who of course is also a reader) actually said he would not read any work by an author who leaves him hanging with a cliffhanger. Rather extreme, but that's what he said (although I doubt he really meant it).
As with my previous comments on chapter length, I don't write a novel with posting chapters on SOL in mind. I write the novel with the expectation the reader can simply "turn the page" to start the next chapter. So if the chapter is short, all they have to do is start the next chapter. If a chapter ends with a cliffhanger, all they have to do is start the next chapter. However, when posting a chapter at a time on SOL, the next chapter might not be available yet.
At least it's not as bad as a TV show when the season ending episode ends with a cliffhanger and you have to wait the entire summer to find out what happens. I post chapters on a regular basis.
Cliffhangers, like every other technique in literary fiction, can be abused, but there's a place for cliffhangers.