You can introduce tweens to safe social networks where they can network and chat, Kidzworld is one. Some parents use safety software and online monitoring services for added protection. Others feel that teaching a child safe Internet practices and developing a strong level of trust works better and allows a child to develop independence. Open lines of communication are very important. Watching for personality or behavioral changes in your child that could signal potential trouble is important also.
Parents do play a greater role in their child's decisions than they may lead you to believe sometimes. Set the tone. You care because you love them and with the rapid advancement of portable technology, providing Internet safety for our children will probably remain challenging for all of us!!
Best wishes to you and yours! :)