Suggestion: "quick summary"
 

Some discussion boards (fatwallet is a notable example) permit the creation of a "quick summary" post immediately below the OP. This proves useful for summarizing the content of lengthy threads without imposing the full burden on anyone in particular.

The "quick summary" could be edited by anyone, as it is at fatwallet, or by the OP, mods, or some combination.

Does the BB software support such a thing?

See an example here: http://www.fatwallet.com/t/52/711457/

you're looking for a wiki post option.

I have to say that I've been thinking for a while in some threads this would be extremely helpful (such as those that are extremely long and cause the OP to update their own post, or cause people to read through xxx pages to see if anyone has experiences.)

I'm not sure if the BB software can support it, but I think it would be a great idea. I know that Flyerguide.com has a wiki, but I think it is definitely underutilized with regards to miles & points.