I posted about this before so I'm starting it here. On another website I frequented there was a similar sandwich thread. It was fun hearing the ideas that people had put together.

I'll start it off: 

Turkey club on pumpernickel. Top it with sharp cheddar, bacon, lettuce, tomato, cranberry sauce and a slice of granny smith apple on top. You can butter the outside of the bread to increase the caloric intake and toast it, or just toast it as is. Either way, it's phenomenal. The apple is the kicker. Using the right cranberry sauce is key as well. Using the one that is just cranberries, orange juice and sugar is perfect.

Which also reminds me of a great thanksgiving leftover sandwich: Turkey, rye, cranberry sauce and brie cheese toasted in the oven.