Firstly, how experienced are you with Game Maker?
The tutorials hopefully tell you what each piece of code is doing, so you can recreate it with dnd. After googling around a bit, I've found an excellent reference. Unfortunately, this converts dnd to code, not the other way around, that would be a tremendous amount of work. However, if you skim the pdf, it should be manageable.
My search query was "game maker drag and drop to gml", in case you'd like to find more.
As for functionality, most 2D games without too much logic going on can be done with dnd. Think of platformers, schmups, racing games, top-down shooters, etc. In theory, even more advanced games can be done, like RTSes, but the dnd would be too verbose for that I think. Try to stay away from complex AI and algorithms, and you should be fine.