A page-turner was defined as a book you couldn't put down, which of course varies from person to person. Michael Burstein's example was The DaVinci Code, which Jim Macdonald hadn't been able to finish (he read the first chapter three times). My example is usually Dorothy Dunnett, especially Pawn in Frankincense. Nomi Burstein said her page-turners often were books that didn't work for others, but I agree The Westing Game is a great example.
Jim Macdonald noted there are three basic types of plots which can be variously combined:
1. "How do I get home?"
2. "Who are those guys?" (Debra Doyle added, "And why are they shooting at me?")
3. One damned thing after another.
All of these generate plot and, if the dilemmas are serious enough, make for good page turning novels. Michael Burstein had tried to analyze the structure of The DaVinci Code and noted that the text would ask questions, particularly at the very end of a chapter, leading you to want the next chapter without stopping. This led to a discussion of cliffhangers, most of which I can't remember well.
For me, page-turners are made by emotional involvement in the characters and not knowing what will come next, particularly if there's some intense angst going on. Strangely, I've found certain romance novels to be page-turners, even though their outcome is pre-determined; I think in that case it's wanting to know what will happen next that's the issue, not what will happen at the end; process rather than final resolution.