Well, I think it really depends on your chapter...for the historian, I think generally it's a good idea to keep a written record of the major stuff that happens (good and bad!) as well as a scrapbook. And, if there's not another position, a webpage, as well.
I'm not really sure about rush and new member educator. My advice for NME is to actually GO somewhere for the pledge retreat! That's my biggest complaint about my pledge period.
Good luck, and keep posting!