Use a combination of threads and outlines.

Use threads to present new ideas, and to get quick feedback, while extracting the salient points and inserting them in their proper places in outlines.

 

Threads and outlines should be cross-referenced, so that if you're reading a thread, and want to find where the points appear in the outline, you just follow a link. Similarly, if you're going through the outline, and you want to hear the ideas in the context of the discussion in which they emerged, you just click a link to go there.