Lobster "shepherd's pie" recipe
Lobster shepherd's pie sounds very interesting though personally I would never combine mashed potatoes with seafood mostly because I find mashed potatoes to be overwhelmingly heavy. Try making a lobster pot pie: http://www.foodnetwork.com/food/recip... and use lobster stock by boiling the shells and just top it off with a simple puff pastry. Good luck.
if you're looking for something different to do w/ lobster...my absolute favorite combination is mac and cheese w/ lobster...yum yum...here's a great recipe:
i also had a friend who would make a fish pie that you could surely substitute lobster with...basically, fish, rice, boiled eggs, carmelized onions all wrapped up in a pie crust and baked. i think it is a russian dish.