Is there an ignore button on the Jolt forums, or some way to disregard posts made by a particular member?
The Most Glorious Hack
Click their name, select View Public Profile, and then Add <name> to Your Ignore List.
Is there anyway to ignore an entire thread, so that it doesn't come up on the main page? I don't mean ignore all the posters in it, but the thread itself.
I'm guessing the answer is no, but if there is a way of doing it, it would be useful.
No, there isn't. That's a feature of the software, so you'll have to take it up with Jelsoft.