Kumquats. Tiny oranges the size of cherry tomatoes that taste like lemons. Not really good for a quick snack, and really hard to make juice with. Better left for people making preserves.
Passion fruit juice. Maybe one day we'll find an actual passion fruit. Tastes like mangoes.
Eggplant. Sort of weirdly bland and peppery at the same time. Not sure it's worth the bother of preparation.
Star fruit, product of Taiwan. Great for garnish, but not much to eat. Tastes like an apple collided with a pear.