I wonder how many photos are there about food photography, Alamy for example gives some tips for shooting food photography. It's worth to take photos about food photography, knowing there are millions ? Probably some rare food are not shooting yet.
This the Alamy tips Web page. 
I found it dead simple to find unexplored food niches that were/are common (heck, just look at SS for something like "fries and gravy". There's only a couple in the first 100 or so, the rest are poutine).
Nice article with some good tips and some lovely pictures.