Is there a way (maybe using some script in nautilus or something) so that you can drag files with the right mouse button and when you release, you're shown the context menu?
If it can even be achieved using some modifier key + left button, I'm ok with it. But Shift + left button (lb) forces a move, Ctrl + lb forces a copy, Alt + lb does a "move window", Super + lb does… well… nothing special, I believe.
Best Answer
If you Middle-click drag and drop (or press Alt after you've started moving the icon so that it doesn't trigger the window move) and then let go of the file a context menu shows up giving you the choice of Copy, Move, link, etc.
Example dragging a file onto my desktop:
The cursor will have a little question mark by it, then when you let go this pops up:
Someone filed a bug report with Nautilus to support right click drag and drop but the developer deemed that unnecessary.