I like spinach omlette - cook/wilt the spinach first in some butter then remove it from the frying pan. put the beaten eggs in the pan and cook the omlette on one side, turn it over then add the spinach and an ounce or two of cheese to the top. When the bottom of the omlette is cooked fold in half and serve.
Cheese, leeks and eggs go well together - i used to make cheese and leek quiche, i guess you could do a pastry free one. Fry up the chopped leeks in some butter, add the eggs and cheese and cook until set.