There are few things (some, but not too many) that are actually evil in themselves until a person allows them to control him/her instead of controlling them, and being, in turn, controlled by God. A television set is just a box with wires, and can be used for God's glory: watching a Bible class, an uplifting/spiritually encouraging movie, etc. But when you start sitting in front of it all the time or using it to feed your mind with unbiblical or ungodly philosophies or pictures, then it does become evil. The same can be said for food, music, hobbies, anything!
With that said, I am going to confess something to you. I'm not going to confess a sin, just a fact. :-)
I got a facebook account! Yes, I did. After all I've said about how terrible it is and how I'd never get one... And here is what Mrs. Havener said on my first status about starting it: "Use it for God's glory and you will not be disappointed!"
It's true. We are to do all for God's glory, even if it is a facebook account. I can use a facebook account to share what the Lord is doing in my life and encourage others spiritually. On the side, I can also keep in touch with my distant (miles) family and friends that I don't get to see/talk to often, and hopefully promote my books when they get published. The key is: I must control it, not let it control me; I must let God control me, not facebook! And so it is with everything else in life.
"Whether therefore ye eat, or drink, or whatsoever ye do, do all to the glory of God" (1 Corinthians 10:31). May it be true of all of us!