In the comments to this post, Sue mentioned that she likes to mix a little bison meat with her ground beef when making burgers at home. Now, they’re pretty much impossible to get at fast food places, but burgers made from exotic meat (not beef) are actually some of my favorite types of burgers.
There’s a restaurant about 10 minutes from where I live that serves Bison Burgers, and they’re fantastic. I actually prefer bison to beef when I can get it, the flavor is actually different, plus the meat is leaner.
Other substitute burger meats that I’ve tried are emu, which is a lot like a super lean ground beef (and delicious) and elk. I really do enjoy an emu burger, but they’re almost impossible to find here in the midwest. I suppose I could start ranching emus and set up my own restaurant, but that seems like a lot of work to get an emu burger.
You could also check out Exotic Meats which can ship a lot of different varieties of meat to 32 different US states. Or, if you really want to make deer burgers, you could go hunting. One of these years…