Any type of game can be hunted without a dog, it is just up to the hunter to know their limits and make sure that they are not reckless in their shot choice.
Ducks and geese are obvious choices over decoys and shallow water, although i know people do use rods/reels to cast big lures over their birds and retrieve them in deeper water.
For upland hunting if you are hunting alone it will be much tougher than if hunting with another person. Chukars and Pheasants would be the birds of choice if i were going upland hunting without a dog. Usually you can find them in narrow strips of cover and they are pretty flighty so they will flush without the aid of a dog. Quail are generally in areas that are brushier and make retrival a problem. In fact i would rather hunt chukars without a dog than with one that is poorly trained. I use my dog for retrival 90% of the time when hunting chukars. She does help scent some birds but mostly she is right by my side. When i was guiding i cant tell you how many guys wanted to frown upon my lab's ability to hunt chukar and would unleash their pointers. A great pointer is a very fine hunting dog i am sure, but i have yet to see a great one. But i digress..
The number one rule is to make sure you mark where your bird falls. Go immeadiately to the area and drop your hat or pack. work downhill from their and look for feathers. Chukars especially, can roll a long ways.
I hunt grouse without a dog (well, I sometimes take my beagle but he is next to worthless as a bird dog). I primarily shoot at non-flushing birds that are stationary. Now a lot of people will tell you that my hunting practice is very un-sportsmanlike, and in most instances I would agree. However, the way I get around that ethical dilemma is that I hunt with a bow. When hunting grouse using archery equipment a dog is just a hinderance since even the best of archers find it difficult, to say the very least, to successfully shoot a flushing grouse. In fact a dogless hunter with a shotgun has a decided advantage over a bowhunter. Even so, there are plenty of traditional bowhunters out there that will tell you that successfully taking a grouse with stick and string has a sense of satisfaction akin to taking a fish with a fly. In my book there's nothing like stalking grouse with a longbow or recurve.