Your daughter is too young to have a Myspace page. You have to be 14 to start one. That said, there's nothing stopping a child from lying about their age to get a Myspace account. Myspace isn't any worse than any other websites, though.
I find that Yahoo is the worst for bahavior that is unsuitable for children. I used to play Yahoo pool, euchre, dominoes, and many other games that you can play against other people. I cannot een begin to give you an estimate on how many times people have hit on me in Yahoo game rooms(and I'm talking all out requests for activities I don't think we should name here.). That's part of the reason that I don't go there anymore. I've not encountered nearly anything that alarming on Myspace.
The internet is always going to be a risk for parents. The key is to minimize the risks. This is not done by banning Myspace, but by monitoring what is going on. I plan to start by not allowing my son to have internet access in his own room. We have a family computer in the dining room(I'm using it now). I plan to allow him to have a computer in his room when he's older, but not internet. If he wants to go online, he can use the family computer, so I could easily slide up behind him as pek at what he's up to. This will also teach him about compromise within the family. With most children having computers and TVs in their rooms these days, it seems that noone compromises anymore...but that's another topic.
Here is where I might get a little long winded. But, I hope this is helpful all the same. I am about to share some of my best tips for monitoring family computer activities.
1- Don't, under any circumstances, tell your kids what you are up to. This will make it harder for you to catch problems later. If you find something you want to confront your child about, just say "I know_____...." They don't need to know how you know.
2- Check the history bar on your browser frequently.
3- Check your internet options settings, to make sure that the history bar and cookies don't get deleted too frequently, just to make sure that you are not missing opportunities to check this.
4- Search your hard drive for suspicious activities. This is done by clicking start, selecting Search. If your kids use the computer under their own Windows desktop, run a search on your child's name. Every file connected with that user will display on a list. From there, it should not be too hard to identify files that seem off. It also can be helpful to run a search for words commonly associated with unsavory sites(I imagine I don't need to list the words here). This should be very informative. Keep in mind that you should open any files that trully concern you, though, just to make sure that you are not wrong about the content.
5- If your child has a messenger account, learn how to keep archives of conversations, and try to avoid letting your child know about this feature. I know in Yahoo Messenger this is done by clicking messenger, selecting preferances, then selecting archive. Make sure the bubbles near Save my call history and save my messages are checked. To check the conversations, just click contacts, select message archive, and it all there.
6- You might also consider insisting on knowing your child's passwords. If your child has nothing to hide, this shouldn't be an issue. My nephew refuse to give my sister his passwords, so I helped her password protect the computer, and she refused to give HIM the password. Internet access is a privledge, not a right. And your right to know your child is safe outweighs the child's right to privacy.
Might seem harsh to some, and I'm not saying all of the above actions should be used all of the time. But, if there is a concern, it's good to know some of the tools you can use to know what you are up against, and how to solve the problem.