The higher the capsacin, the better. So load up on chili pepper counterparts like Habañero but if that's a little to spicy for your taste, try jalapeño, cherry pepper and Spanish pimiento.
For a nice, Indian side dish courtesy of my friend Sibia, try sautéing some onions in olive oil, add green beans, turmeric and chili powder and cook a bit more but be sure beans are still crunchy. Add salt and pepper to taste.