I jump seat home and to work often with Northwest and usually ride on the 757 and A320/A319. The 757 always seems to be at .80-.82, depending on whether they're running late or not. The Airbuses are always at .78.
Occasionally I have been on Fed Exs A300 and A310, they seem to be between .78-.80 all the time.
I have never been on a 717, but the Dc-9 cruises at .75and the MD80 between .76-.78.
As for the rest I'm not sure, one thing to remember is that an airline has the last say in cruise speed. The Mmo is the limiting factor, but most airlines, especially with the newere computer controlled aircraft, set the speed that is the best for economy, so who knows, what one airline uses can be diffrent for another.
Hope this helps