Even when I was 8 and started getting snes games I kept all the boxes and manuals and sorted them alphabetically.
But there was at one point where a friend had told me a store would take my games and give me credit to buy new games and it wasn't a pawn shop. I couldn't believe it, anyways I ended up bringing about 6 64 games, 5 PS and 5 GB-GBC games and ended up with like 70$ in store credit and bought FFT and a memory card. Looking back on it I really really regret it, they were all in good condition and boxed.
Anyways I keep all my games now, I really wish EBgames had some sort of law that required kids under 18 to have parents with them before they can trade in stuff.
My current collection is rather lovely especially my snes collection which i'm addicted to.