There are some good samples in this thread.
One thing to be careful of when using drag+drop is hitbox sizes. It's quite common to have a sprite like a piece of treasure that has a fairly small hitbox that is dragged around the level, but it makes clicking on the actual sprite very hard. Usually you want a large hitbox for clicking and dragging and a small hitbox for actual game collisions. I suggest having a pinned sprite that is used for interaction with the mouse cursor and keep all collisions to the game world on the treasure sprite itself.
It might seem obvious in retrospect, but when you end up fiddling about for 3 hours because you thought it was a bug elsewhere in your code you end up feeling a bit of the fool <img src="smileys/smiley9.gif" border="0" align="middle">