Creating contact sheets in InDesign is another one I am always forgetting the short cut keys for.
1. Choose File > Place, select multiple images, and choose Open.
2. Hold down Ctrl+Shift (Windows) or Command+Shift (Mac OS) and click or drag.
3. While still dragging, release the other modifier keys and press the arrow keys to determine the number of rows and columns. Use the Up Arrow and Down Arrow keys to change the number of rows and the Left and Right arrow keys to change the number of columns. To change the spacing between frames, use the Page Up and Page Down keys or hold down Shift while pressing the arrow keys.
4. Release the mouse button to place the grid of images.
Original Adobe blog/tutorial here