I was going to mention The Sims in my list as well! I could probably survive without it, but I know when I was overseas earlier in the year I was getting intense cravings to play it and downloaded that terrible, incredibly subpar app to try and fill the void. So maybe I would struggle?
For me it would be the internet, TV and Sleeping whenever I want.
It's funny how most people have said the internet. If this were the first series and this question was asked I wonder what the most popular answer would be. Might be the internet but I don't think in 2001 everyone had access to the internet like we do in 2013.