not neccesarily a thanksgiving specific appetizer, but one of my all time favorites is beef crustinis.
take a nice load of baquette bread, slice into 1/3" pieces, brush with garlic butter and toast. then take a nice piece of prime rib or top round and cook to medium rare. slice into small pieces. take some butter at room temperature, and toss in a food processor with a little garlic, salt, and roasted red peppers.
now take your toasted bread, and spread a little of the red pepper butter on them. place a slice of beef, a piece of roasted red pepper, and a scallion on it and enjoy.
relatively simple and quite delicious.
