Masking tape is another trick that may be convenient if a magnet isn't on hand. Take a big piece, pick up as many as you can, pull them off, repeat. Use a new piece of tape if it loses its stickiness.
Edit: The technique is to use one hand, slowly pull the length of tape through the air and gently put it down so it lays flat and touches as many items as possible. Use your other hand to glide down the length is the tape, pressing it down onto any objects underneath. Then pick it up whichever way seems to not drop the items.