rambotan-red, fuzzy thing. Sweet. Get the "cling" variety, not the "freestone" if you can. That way you don't get paper-texture seed coating along with the flesh.
mangosteen-"Queen of fruits", sweet and very tasty. Purple outer shell, white flesh. Outer shell often has a small amount of very sticky yellow sap, but it's easy to avoid.
salak-has a skin like snake scales, pretty cool looking. Something like a cross between an apple and a pineapple, astringent.
pitahaya (South America) - yellow, white flesh, sweet and very tasty. Same basic fruit as the dragonfruit (SE Asia), which is red with white or red flesh. Dragonfruit is better looking, pitahaya tastes better.
Malay apple - very mild taste. No seeds.
langsat - small fruits with a thin skin and translucent white flesh around a seed. Sweet. Juicy.
carambola - "starfruit". Sweet and tart...sort of like a pineapple, but a bit more tart. Tasty and neat-looking.
Not for everyone:
jakfruit--strong sweet odor, somewhat thick taste. BIG fruit. Yellow flesh around seeds in non-edible matrix.
durian--big spiky fruit. VERY strong smell. Yellow or red flesh around seeds in non-edible matrix. Few Westerners go in for it. Very fatty pulp with a strong taste.
borojo--very powerful scent and taste. Usually used in drinks or as flavoring, too strong for straight-up eating. Some say it cures cancer, it's certainly chock-full of antioxidants etc.
Unfortunately, few tropical fruits taste nearly as good after being shipped internationally.