1. Fresh fish -- Depending slightly on your definition of "fresh", but I assume "on the pier, recently off the boat" counts.
4. Thai food
5. Chinese food
6. Ice cream
11. Moreton Bay Bugs
12. Clam chowder
19. Cream tea -- Hmm. I'm not 100% sure I've had scones with clotted cream, and I don't think I've ever sat down and done this properly. (It sounds like proper cream tea is all about the properly-constructed meal.) So I'll count this as a "no".
20. Alligator -- I think the answer is yes, in a more complex dish. But I'm not completely sure.
21. Oysters -- Once, as sushi. Once was enough.
25. Greek food -- Not really my cuisine of choice, but I've had a bit.
27. Mexican food
28. Squid -- Mmm; squid. (One of my favorite sushi varieties.)
29. American diner breakfast -- Pancakes and greasy bacon. Nothing quite like it.
31. Venison -- At several SCA events.
32. Guinea pig
33. Shark -- I have a vague inkling that I've tried it, but I'm not sure.
35. Paella -- A relatively recent discovery (past few years), but I've found that I adore it when well-made, abundant with a riot of random seafood.
40. Australian meat pie
42. Durian fruit -- The BBC description includes "it's also notorious for emitting a pungent, 'distinctive' odour (think clogged drains in August)"
43. Octopus -- Almost as good as squid
45. Roast beef
46. Tapas -- Discovered the same day I first tried paella. Wonderful stuff, but I want a better option than Solea, which is a smidgeon over-expensive and was only good.
47. Jerk chicken/pork
48. Haggis -- Not 100% certain, but I believe I tried it at the Glasgow Worldcon ten years ago.
50. Cornish Pasty -- Somehow, ending with madamebuttery's specialty just seems somehow appropriate. My favorite Pennsic lunch for several years...