Seldom do I agree with everything anyone has to say, but I find myself in complete agreement with the folks from the "National Institute on MEDIA and the FAMILY"...and they have *lots* of advice. I wish you didn't have to sign up for an account to download the parent guides, but they are worth it. As with any site that asks for a username and password, create a new one (not the one you use for finances/email/etc) and store it in a password manager if necessary. Look for advice related to Social Networking, Online Gaming, Cell Phones, Parental Ratings, Emerging Technologies, MySpace, Facebook, and other areas.
The Institute also has some "plans" to serve as a contract between child and parent for rules related to online activities, but I prefer the one from the Family Online Safety Institute. Its length makes it less reasonable, but it is rather inclusive...including a reminder for parents not to overreact when kids show them something bad.
I'll use a quote from the Parent Buying Guide to close this post.
When we buy our kids everything they want, they miss out on some of the things they really need to succeed - like perseverance, generosity and the ability to delay gratification. Some things you can’t buy at a store. Does this mean we can’t buy our kids anything, ever? Of course not. It does mean it’s okay to say no sometimes.
Spend twice as much time, and half as much money as you can afford, with your kids.