Ground turkey or chicken are great substitutes with less cholesterol but like pp's have said, you still have to make sure you get lean ground meat, otherwise it will have as much if not more fat than ground beef.
For turkey burgers I saute some diced onion and bell pepper (I prefer red or orange, the green ones taste too bitter to me) with a bit of minced garlic in a teaspoon of oil until the veg is soft. Then I mix the sauteed veg in with the ground turkey along with either bbq sauce or terriaki sauce for some flavor. They cook up really moist from the vegetables and flavorful from the sauce. Don't go overboard with the sauces though, they usually have a lot of sugar and that will also add tons of unnecessary calories.
I also sub ground turkey or chicken in chilis and pasta sauces. If doing this though, I'll brown the meat then let it simmer a bit in the sauce, then I break it up by mashing the meat in the sauce with a potato masher. It really breaks up the meat and the texture is more like what you get from ground beef in sauces.
Meatballs can be good with ground turkey too but I usually do a 50/50 mix of lean beef and lean turkey for better flavor and texture.