I made some great kabobs recently that would adapt well to turkey burgers. I used a very lean cut of pork and it turned out very tender, so it should adapt well to either very lean beef or turkey/chicken.
500 g meat
2 Tbsp chick pea flour (besan) - you could substitute bread crumbs.
1/2 a medium onion
1 small bunch cilantro
1 T lime juice
1 small egg
3 cloves garlic, crushed
2 cm ginger, chopped.
Roast 1 2 cm stick of cinnamon, 5 cloves, 1 t cumin seed, 1 t coriander seed, 1/2 t cardamon seed, 1 t black peppercorns in a dry pan until toasted. Cool and grind in a mortar and pestle or coffee grinder.
Very finely chop the cilantro, onion, garlic and ginger in a food processor. Add the meat and blend well - you want the meat very finely ground. Mix by hand with the besan, ground spices, plus 1 t salt and 1 t (or more to taste) cayenne pepper, egg and lime juice until well blended. Form into patties and bake or pan fry (or put on skewers and make kebabs).
The result is intensely flavourful, very tender, even with low fat meat, and nicely spicy, and can be eaten straight. As a burger, I would probably top it with lettuce, thinly sliced onion, tomato, and maybe a bit of ketchup.