I've got the payware Flight1/Coolsky Super 80 and aliased my EHO MD-83 to this as it's really detailed and nicely different to Boeing & Airbus panels

As for freeware, Tom Dennis has done a good one which looks quite realistic - on Flightsim.com it's called "md8x9xcp.zip" and there's a fix file to go with this called "md8x9xpt.zip".