Elka alerts me to an oncoming migraine. She also pesters my fiance if his blood sugar is low. These are things we noticed her doing and have happily reinforced. She isn't "officially" a service dog; I haven't trained her for public access, my migraines aren't limited enough to require her with me at work, etc. but for all intents and purposes, she's my migraine dog in the home, at the very least.
I didn't get a Doberman with this in mind, though. It's just been an added bonus.