There are lots of "rules" on how kids (and parents) can be use the Internet but the most important rule is that parents and kids agree to a set of criteria. Here, based on "Kids Rules for Online Safety" and "Guidelines for Parents" are two pledges that kids and parents can take. They should be printed out, signed by both kids and parents, printed out, and posted near the computer.
Parents' Pledge (Click here for printable PDF Version -- requires Adobe Acrobat*)
* Click here for free download of Acrobat