My most successful/exciting fruit discovery is the cherimoya. It has a green skin that looks kind of like a weird artichoke, and great big seeds throughout the flesh. The fruit itself tastes kind of like a banana, but better. After thinking about it awhile, I figured out that they kind of taste like banana candy, like banana Runts. However, it doesn't have the artificial candy taste, and is good for you--it's perfect!
I looked the cherimoya up on Wikipedia, just like I do with every new thing I become obsessed with. It says Mark Twain called the cherimoya "the most delicious fruit known to men." I can't disagree!