But my question is: what was the point of the list? If Hermione was using it to maintain the secrecy of the DA, then she had to tell the members that there would be consequences for telling in order for it to work. However, if the point was just to punish anyone who talked, then Hermione did an excellent job -- but her actions do not speak very highly of her, any more than in the House Elf instance I mentioned.

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I think you've got a good point there. If you are going to bother to put a jinx on the paper, why not make it so that whoever signs it is unable to divulge the DA's secrets? It would be the next best thing to the Fidelius Charm. I guess one could argue that Hermione felt that it was not very likely for someone to betray them, as they were doing something to help everyone pass their practical DADA exams and go against Umbridge's ridiculous regime, so she just wanted to make sure that if someone does betray them, they will regret it right away. Still, it's not like Hermione to take security lightly.

I think the main point is that the curse was triggered only by the act of actually telling the secret. the mere fact that one would be tempted to tell the secret wouldn't be enough to trigger it. What I'm trying to say is that Hermione is too fair to punish someone for something they didn't yet do. The only choice she had was to make sure the would know with dead certainty who the spy was. Remember, this was only slightly over a year after they learned the truth about Sirius and Wormtail. With that memory fresh in mind she would want to make sure that the right person would be held responsible.
While it may seem a harsh punishment that Marietta had to live with her pimples for years, it is no less than what Umbridge had already done to Harry. The scars on his hand were still visible two years after the fact as well. And if Dumbledore hadn't intervened on Harry's AND Marietta's behalf who knows what might have happened. As it was, Marietta's decision to betray the DA, and her friend Cho, gave Umbridge free rein at Hogwarts and resulted in Dumbledore's suspension - a definite turn for the worse.
So I think the curse was the right thing to do at the time. It definitely stopped Marietta from disclosing any more of the DA's secrets and it served the second and in my opinion even more important purpose of letting the other members know who the spy was. If the whole affair in the office had ended differently it would have been possible for any remaining DA members to keep in touch without the constant fear of having the spy still among them. Hermione simply tried to be prepared foe every eventuality.

not only is this terrible punishment, it's silimar to harry's scars. first of all, harry got those scars for his own backtalking- marrietta had nothing to do with that. the reason they are silimar is that this is bringing hermionie down to umbridges level- punishinig a student for disloyalty, and causing them much pain.

what i don't agree with is leaving the scar for over a year. hermionie lost harry and ron when she turned harry's firebolt in. she was miserable- freindless, and went crying to hagrid. i think it really changed how she acted with them- she valued their freindship much more, and didn't turn them in again (for example, she didn't turn the marauder's map in). now she dooms someone else to silimar torment (who would stay friends with the sneak?) but not only for a week, but for years. this was punishment. how would hermionie had felt if her friends and others abandoned her for a long period of years, because no one would forget her betrayl because there it would be written on her forehead. now she's caused marrietta this same punishment. it's a huge excuse for everyone to bully her, and no one would move on and forget because it was still spelled out on her face to remind them.

That's a good question. Maybe part of Hermione's charm had the stipulation that if in fact there was a snitch, that a simple apology would make the "pimples" go away. It doesn't seem that Marietta did since she still has the scars.