Exactly 50% of the time I keep the extra useless papers, and exactly 50% of the time I throw them all out. I don't need to read Safety and Health precautions, or subscribe to Nintendo Power with every single DS game I buy (which is the worst for all that wasted paper ;_

. Even when they are bulky and make it so that the instruction manual barely can squeeze under the hooks, I'll sometimes keep them. Lately I find that there are so much more than before that I won't bother to sort out what looks decent and what is junk.
French manuals in all Canadian games also fall under junk but I now keep them 100% of the time for the future, when I might want to cut the pictures out of them or scan them.
Jam it back in, in the dark.