The following are meats that I have eaten separated into categories that I deem them to be appropriately in, even if not so "unusual" in my eyes since others so far in this thread/friends have considered them unusual:
"Mainstream" meats
Lamb - my favourite
I've had an Iranian breakfast (cooked on special occasions) which is basically an entire sheep's head in a stew when I visited my family in Iran. I was only 11 at the time so I didn't get too adventurous and stuck mainly to the soup it was in, but the tongue was nice. My dad got stuck right in there having brain and eyes and whatever else.
Beef
Chicken
Pork - not too keen on pork, but ham/sausages/bacon are alright now and then.
Specialist/luxury/more expensive meats
Venison (deer) - Would be my favourite over lamb if I could afford to have it regularly
Duck - Never buy duck crown. Always get duck breasts. Otherwise a great tasting meat, especially when in China
Goose Liver - specifically in the form of paté. Amazing
Pousin (small bird) - Basically like a small chicken, but nicer
Buffalo - More expensive beef. Not worth it to be honest
Wild Boar - Quite nice
Regional delicacies
These are thing I've had abroad that are relatively common there, but are rare/non existent at home.
Snails (France & China) - The French do them better, but the Chinese do it decently as well. French make it hot with garlic and butter whilst the Chinese serve it ice cold (as in, over ice after cooked so it's fridge cold) with a bunch of spices
Pigeon (France) - Tough. Just a really tough meat. Probably cooked wrong in that restaurant but still.
Rabbit (Spain) - It was alright, but I'm definite that a testicle was in there as well, which has put me off it indefinitely (especially since I had it when I was 14)
Scorpions (China) - Tasteless crunchy things
Snake (China) - Chewy like rubber and odd. Avoid
Frog (China) - Not bad, but nothing special. Odd cross between fish and chicken (more fish-like in taste, chicken-like in texture)
Seafood
Some people I know wont touch anything that once lived in water, so for them everything on this list would be considered unusual.
Cod
Black Cod - Amazing
Haddock
Salmon - sashimi :3
Lemon Sole
Prawn/Shrimp/Scampi/King Prawns/Tiger Prawns/Langoustines
Mussels
Crab - Best crustacean in almost any form. Personal favourites are soft shell crab (sushi) and black pepper crab (Singapore/Malaysia)
Lobster - Crab is better and cheaper
Caviar (fish eggs) - Not that keen
Mackerel
Tuna
Fatty Tuna (can't remember the exact name) - Amazing
Squid
Sardines
Eel
Bream
Clams
Oyster - Fucking disgusting
And to top off the list, the maggot at the bottom of a tequila bottle (I know that the drink that has the maggot at the bottom isn't called tequila but I can't remember the name).
There's bound to be a few that I've missed, especially with respect to seafood since I've been to a few restaurants (or even just my dad cooking at home) where I've had "today's special", which was just random white fish. Also, living in England, I've probably had horse without my knowledge.